Shumaker, D E; Woodward, C S
2005-05-03
In this paper, the authors investigate performance of a fully implicit formulation and solution method of a diffusion-reaction system modeling radiation diffusion with material energy transfer and a fusion fuel source. In certain parameter regimes this system can lead to a rapid conversion of potential energy into material energy. Accuracy in time integration is essential for a good solution since a major fraction of the fuel can be depleted in a very short time. Such systems arise in a number of application areas including evolution of a star and inertial confinement fusion. Previous work has addressed implicit solution of radiation diffusion problems. Recently Shadid and coauthors have looked at implicit and semi-implicit solution of reaction-diffusion systems. In general they have found that fully implicit is the most accurate method for difficult coupled nonlinear equations. In previous work, they have demonstrated that a method of lines approach coupled with a BDF time integrator and a Newton-Krylov nonlinear solver could efficiently and accurately solve a large-scale, implicit radiation diffusion problem. In this paper, they extend that work to include an additional heating term in the material energy equation and an equation to model the evolution of the reactive fuel density. This system now consists of three coupled equations for radiation energy, material energy, and fuel density. The radiation energy equation includes diffusion and energy exchange with material energy. The material energy equation includes reaction heating and exchange with radiation energy, and the fuel density equation includes its depletion due to the fuel consumption.
Adaptive Implicit Non-Equilibrium Radiation Diffusion
Philip, Bobby; Wang, Zhen; Berrill, Mark A; Rodriguez Rodriguez, Manuel; Pernice, Michael
2013-01-01
We describe methods for accurate and efficient long term time integra- tion of non-equilibrium radiation diffusion systems: implicit time integration for effi- cient long term time integration of stiff multiphysics systems, local control theory based step size control to minimize the required global number of time steps while control- ling accuracy, dynamic 3D adaptive mesh refinement (AMR) to minimize memory and computational costs, Jacobian Free Newton-Krylov methods on AMR grids for efficient nonlinear solution, and optimal multilevel preconditioner components that provide level independent solver convergence.
Radiation temperature of non-equilibrium plasmas
Arunasalam, V.
1991-07-01
In fusion devices measurements of the radiation temperature T{sub r} ({omega}, k) near the electron cyclotron frequency {omega}{sub C} and the second harmonic 2{omega}{sub C} in directions nearly perpendicular to the confining magnetic field B (i.e., k {approx} k {perpendicular}) serve to map out the electron temperature profiles T{sub e}(r,t). For optically thick plasma at thermodynamic equilibrium T{sub r} = T{sub e}. However, there is increasing experimental evidence for the presence of non-equilibrium electron distributions (such as a drifting Maxwellian with appreciable values of the streaming parameter {omicron} = v{sub d}/v{sub t}, a bi- Maxwellian, and anisotropic Maxwellian with T {perpendicular} {ne} T {parallel}, etc.,) in tokamak plasmas, especially in the presence of radio-frequency heating. Here, we examine (both non-relativistically and relativistically) the dependence of T{sub r} on {omicron}, T{perpendicular}/T{parallel}, T{sub h}/T{sub b}, n{sub h}/n{sub b}etc., where n{sub b}, n{sub h}, T{sub b}, T{sub h} are the densities and temperatures, respectively, of the bulk and the hot components of the bi-Maxwellian plasma. Our bi-Maxwellian results predict that the ratio T{sub r}/T{sub e} is a very sensitive function of the ratios n{sub h}/n{sub b} and T{sub h}/T{sub b}. Further, these relativistic and non-relativistic results satisfy the well-known limit c {yields} {infinity} correspondence principle'', showing that the intensity of the emission and absorption line is independent of the line broadening mechanism. 44 refs., 2 figs.
Non-equilibrium radiation nuclear reactor
NASA Technical Reports Server (NTRS)
Thom, K.; Schneider, R. T. (Inventor)
1978-01-01
An externally moderated thermal nuclear reactor is disclosed which is designed to provide output power in the form of electromagnetic radiation. The reactor is a gaseous fueled nuclear cavity reactor device which can operate over wide ranges of temperature and pressure, and which includes the capability of processing and recycling waste products such as long-lived transuranium actinides. The primary output of the device may be in the form of coherent radiation, so that the reactor may be utilized as a self-critical nuclear pumped laser.
Investigation of Non-Equilibrium Radiation for Earth Entry
NASA Technical Reports Server (NTRS)
Brandis, Aaron; Johnston, Chris; Cruden, Brett
2016-01-01
This paper presents measurements and simulations of non-equilibrium shock layer radiation relevant to high-speed Earth entry data obtained in the NASA Ames Research Center's Electric Arc Shock Tube (EAST) facility. The experiments were aimed at measuring the spatially and spectrally resolved radiance at relevant entry conditions for both an approximate Earth atmosphere (79 N2 : 21 O2) as well as a more accurate composition featuring the trace species Ar and CO2 (78.08 N2 : 20.95 O2 : 0.04 CO2 : 0.93 Ar). The experiments were configured to target a wide range of conditions, of which shots from 8 to 11.5 km/s at 0.2 Torr (26.7 Pa) are examined in this paper. The non-equilibrium component was chosen to be the focus of this study as it can account for a significant percentage of the emitted radiation for Earth entry, and more importantly, non-equilibrium has traditionally been assigned a large uncertainty for vehicle design. The main goals of this study are to present the shock tube data in the form of a non-equilibrium metric, evaluate the level of agreement between the experiment and simulations, identify key discrepancies and to promote discussion about various aspects of modeling non-equilibrium radiating flows. Radiance profiles integrated over discreet wavelength regions, ranging from the VUV through to the NIR, were compared in order to maximize both the spectral coverage and the number of experiments that could be used in the analysis. A previously defined non-equilibrium metric has been used to allow comparisons with several shots and reveal trends in the data. Overall, LAURAHARA is shown to under-predict EAST by as much as 50 and over-predict by as much as 20 depending on the shock speed. DPLRNEQAIR is shown to under-predict EAST by as much as 40 and over-predict by as much as 12 depending on the shock speed. In terms of an upper bound estimate for the absolute error in wall-directed heat flux, at the lower speeds investigated in this paper, 8 to 9 km/s, even
Investigation of Non-Equilibrium Radiation for Earth Entry
NASA Technical Reports Server (NTRS)
Brandis, A. M.; Johnston, C. O.; Cruden, B. A.
2016-01-01
For Earth re-entry at velocities between 8 and 11.5 km/s, the accuracy of NASA's computational uid dynamic and radiative simulations of non-equilibrium shock layer radiation is assessed through comparisons with measurements. These measurements were obtained in the NASA Ames Research Center's Electric Arc Shock Tube (EAST) facility. The experiments were aimed at measuring the spatially and spectrally resolved radiance at relevant entry conditions for both an approximate Earth atmosphere (79% N2 : 21% O2 by mole) as well as a more accurate composition featuring the trace species Ar and CO2 (78.08% N2 : 20.95% O2 : 0.04% CO2 : 0.93% Ar by mole). The experiments were configured to target a wide range of conditions, of which shots from 8 to 11.5 km/s at 0.2 Torr (26.7 Pa) are examined in this paper. The non-equilibrium component was chosen to be the focus of this study as it can account for a significant percentage of the emitted radiation for Earth re-entry, and more importantly, non-equilibrium has traditionally been assigned a large uncertainty for vehicle design. The main goals of this study are to present the shock tube data in the form of a non-equilibrium metric, evaluate the level of agreement between the experiment and simulations, identify key discrepancies and to examine critical aspects of modeling non-equilibrium radiating flows. Radiance pro les integrated over discreet wavelength regions, ranging from the Vacuum Ultra Violet (VUV) through to the Near Infra-Red (NIR), were compared in order to maximize both the spectral coverage and the number of experiments that could be used in the analysis. A previously defined non-equilibrium metric has been used to allow comparisons with several shots and reveal trends in the data. Overall, LAURA/HARA is shown to under-predict EAST by as much as 40% and over-predict by as much as 12% depending on the shock speed. DPLR/NEQAIR is shown to under-predict EAST by as much as 50% and over-predict by as much as 20% depending
Multi-Modality Pulsed AC Source for Medical Applications of Non-Equilibrium Plasmas
NASA Astrophysics Data System (ADS)
Friedrichs, Daniel; Gilbert, James
2014-10-01
A burgeoning field has developed around the use of non-equilibrium (``cold'') plasmas for various medical applications, including wound treatment, surface sterilization, non-thermal hemostasis, and selective cell destruction. Proposed devices typically utilize pulsed DC power sources, which have no other therapeutic utility, and may encounter significant regulatory restrictions regarding their safety for use in patient care. Additionally, dedicated capital equipment is difficult for healthcare facilities to justify. In this work, we have demonstrated for the first time the generation of non-equilibrium plasma using pulsed AC output from a specially-designed electrosurgical generator. The ability to power novel non-equilibrium plasma devices from a piece of equipment already ubiquitous in operating theatres should significantly reduce the barriers to adoption of plasma devices. We demonstrate the ability of a prototype device, coupled to this source, to reduce bacterial growth in vitro. Such a system could allow a single surgical instrument to provide both non-thermal sterilization and thermal tissue dissection.
Entropy-based artificial viscosity stabilization for non-equilibrium Grey Radiation-Hydrodynamics
Delchini, Marc O. Ragusa, Jean C. Morel, Jim
2015-09-01
The entropy viscosity method is extended to the non-equilibrium Grey Radiation-Hydrodynamic equations. The method employs a viscous regularization to stabilize the numerical solution. The artificial viscosity coefficient is modulated by the entropy production and peaks at shock locations. The added dissipative terms are consistent with the entropy minimum principle. A new functional form of the entropy residual, suitable for the Radiation-Hydrodynamic equations, is derived. We demonstrate that the viscous regularization preserves the equilibrium diffusion limit. The equations are discretized with a standard Continuous Galerkin Finite Element Method and a fully implicit temporal integrator within the MOOSE multiphysics framework. The method of manufactured solutions is employed to demonstrate second-order accuracy in both the equilibrium diffusion and streaming limits. Several typical 1-D radiation-hydrodynamic test cases with shocks (from Mach 1.05 to Mach 50) are presented to establish the ability of the technique to capture and resolve shocks.
Asymptotic analysis of discrete schemes for non-equilibrium radiation diffusion
NASA Astrophysics Data System (ADS)
Cui, Xia; Yuan, Guang-wei; Shen, Zhi-jun
2016-05-01
Motivated by providing well-behaved fully discrete schemes in practice, this paper extends the asymptotic analysis on time integration methods for non-equilibrium radiation diffusion in [2] to space discretizations. Therein studies were carried out on a two-temperature model with Larsen's flux-limited diffusion operator, both the implicitly balanced (IB) and linearly implicit (LI) methods were shown asymptotic-preserving. In this paper, we focus on asymptotic analysis for space discrete schemes in dimensions one and two. First, in construction of the schemes, in contrast to traditional first-order approximations, asymmetric second-order accurate spatial approximations are devised for flux-limiters on boundary, and discrete schemes with second-order accuracy on global spatial domain are acquired consequently. Then by employing formal asymptotic analysis, the first-order asymptotic-preserving property for these schemes and furthermore for the fully discrete schemes is shown. Finally, with the help of manufactured solutions, numerical tests are performed, which demonstrate quantitatively the fully discrete schemes with IB time evolution indeed have the accuracy and asymptotic convergence as theory predicts, hence are well qualified for both non-equilibrium and equilibrium radiation diffusion.
Dynamic Implicit 3D Adaptive Mesh Refinement for Non-Equilibrium Radiation Diffusion
Philip, Bobby; Wang, Zhen; Berrill, Mark A; Rodriguez Rodriguez, Manuel; Pernice, Michael
2014-01-01
The time dependent non-equilibrium radiation diffusion equations are important for solving the transport of energy through radiation in optically thick regimes and find applications in several fields including astrophysics and inertial confinement fusion. The associated initial boundary value problems that are encountered exhibit a wide range of scales in space and time and are extremely challenging to solve. To efficiently and accurately simulate these systems we describe our research on combining techniques that will also find use more broadly for long term time integration of nonlinear multiphysics systems: implicit time integration for efficient long term time integration of stiff multiphysics systems, local control theory based step size control to minimize the required global number of time steps while controlling accuracy, dynamic 3D adaptive mesh refinement (AMR) to minimize memory and computational costs, Jacobian Free Newton Krylov methods on AMR grids for efficient nonlinear solution, and optimal multilevel preconditioner components that provide level independent linear solver convergence.
Dynamic implicit 3D adaptive mesh refinement for non-equilibrium radiation diffusion
B. Philip; Z. Wang; M.A. Berrill; M. Birke; M. Pernice
2014-04-01
The time dependent non-equilibrium radiation diffusion equations are important for solving the transport of energy through radiation in optically thick regimes and find applications in several fields including astrophysics and inertial confinement fusion. The associated initial boundary value problems that are encountered often exhibit a wide range of scales in space and time and are extremely challenging to solve. To efficiently and accurately simulate these systems we describe our research on combining techniques that will also find use more broadly for long term time integration of nonlinear multi-physics systems: implicit time integration for efficient long term time integration of stiff multi-physics systems, local control theory based step size control to minimize the required global number of time steps while controlling accuracy, dynamic 3D adaptive mesh refinement (AMR) to minimize memory and computational costs, Jacobian Free Newton–Krylov methods on AMR grids for efficient nonlinear solution, and optimal multilevel preconditioner components that provide level independent solver convergence.
NASA Astrophysics Data System (ADS)
Richings, A. J.; Schaye, Joop
2016-05-01
We present a series of hydrodynamic simulations of isolated galaxies with stellar mass of 109 M⊙. The models use a resolution of 750 M⊙ per particle and include a treatment for the full non-equilibrium chemical evolution of ions and molecules (157 species in total), along with gas cooling rates computed self-consistently using the non-equilibrium abundances. We compare these to simulations evolved using cooling rates calculated assuming chemical (including ionization) equilibrium, and we consider a wide range of metallicities and UV radiation fields, including a local prescription for self-shielding by gas and dust. We find higher star formation rates and stronger outflows at higher metallicity and for weaker radiation fields, as gas can more easily cool to a cold (few hundred Kelvin) star-forming phase under such conditions. Contrary to variations in the metallicity and the radiation field, non-equilibrium chemistry generally has no strong effect on the total star formation rates or outflow properties. However, it is important for modelling molecular outflows. For example, the mass of H2 outflowing with velocities {>}50 {km} {s}^{-1} is enhanced by a factor ˜20 in non-equilibrium. We also compute the observable line emission from C II and CO. Both are stronger at higher metallicity, while C II and CO emission are higher for stronger and weaker radiation fields, respectively. We find that C II is generally unaffected by non-equilibrium chemistry. However, emission from CO varies by a factor of ˜2-4. This has implications for the mean XCO conversion factor between CO emission and H2 column density, which we find is lowered by up to a factor ˜2.3 in non-equilibrium, and for the fraction of CO-dark molecular gas.
Brantley, P S
2006-08-08
The double spherical harmonics angular approximation in the lowest order, i.e. double P{sub 0} (DP{sub 0}), is developed for the solution of time-dependent non-equilibrium grey radiative transfer problems in planar geometry. Although the DP{sub 0} diffusion approximation is expected to be less accurate than the P{sub 1} diffusion approximation at and near thermodynamic equilibrium, the DP{sub 0} angular approximation can more accurately capture the complicated angular dependence near a non-equilibrium radiation wave front. In addition, the DP{sub 0} approximation should be more accurate in non-equilibrium optically thin regions where the positive and negative angular domains are largely decoupled. We develop an adaptive angular technique that locally uses either the DP{sub 0} or P{sub 1} flux-limited diffusion approximation depending on the degree to which the radiation and material fields are in thermodynamic equilibrium. Numerical results are presented for two test problems due to Su and Olson and to Ganapol and Pomraning for which semi-analytic transport solutions exist. These numerical results demonstrate that the adaptive P{sub 1}-DP{sub 0} diffusion approximation can yield improvements in accuracy over the standard P{sub 1} diffusion approximation, both without and with flux-limiting, for non-equilibrium grey radiative transfer.
Brantley, P S
2005-12-13
The double spherical harmonics angular approximation in the lowest order, i.e. double P{sub 0} (DP{sub 0}), is developed for the solution of time-dependent non-equilibrium grey radiative transfer problems in planar geometry. Although the DP{sub 0} diffusion approximation is expected to be less accurate than the P{sub 1} diffusion approximation at and near thermodynamic equilibrium, the DP{sub 0} angular approximation can more accurately capture the complicated angular dependence near a non-equilibrium radiation wave front. In addition, the DP{sub 0} approximation should be more accurate in non-equilibrium optically thin regions where the positive and negative angular domains are largely decoupled. We develop an adaptive angular technique that locally uses either the DP{sub 0} or P{sub 1} flux-limited diffusion approximation depending on the degree to which the radiation and material fields are in thermodynamic equilibrium. Numerical results are presented for two test problems due to Su and Olson and to Ganapol and Pomraning for which semi-analytic transport solutions exist. These numerical results demonstrate that the adaptive P{sub 1}-DP{sub 0} diffusion approximation can yield improvements in accuracy over the standard P{sub 1} diffusion approximation, both without and with flux-limiting, for non-equilibrium grey radiative transfer.
Non-equilibrium thermodynamics theory of econometric source discovery for large data analysis
NASA Astrophysics Data System (ADS)
van Bergem, Rutger; Jenkins, Jeffrey; Benachenhou, Dalila; Szu, Harold
2014-05-01
Almost all consumer and firm transactions are achieved using computers and as a result gives rise to increasingly large amounts of data available for analysts. The gold standard in Economic data manipulation techniques matured during a period of limited data access, and the new Large Data Analysis (LDA) paradigm we all face may quickly obfuscate most tools used by Economists. When coupled with an increased availability of numerous unstructured, multi-modal data sets, the impending 'data tsunami' could have serious detrimental effects for Economic forecasting, analysis, and research in general. Given this reality we propose a decision-aid framework for Augmented-LDA (A-LDA) - a synergistic approach to LDA which combines traditional supervised, rule-based Machine Learning (ML) strategies to iteratively uncover hidden sources in large data, the artificial neural network (ANN) Unsupervised Learning (USL) at the minimum Helmholtz free energy for isothermal dynamic equilibrium strategies, and the Economic intuitions required to handle problems encountered when interpreting large amounts of Financial or Economic data. To make the ANN USL framework applicable to economics we define the temperature, entropy, and energy concepts in Economics from non-equilibrium molecular thermodynamics of Boltzmann viewpoint, as well as defining an information geometry, on which the ANN can operate using USL to reduce information saturation. An exemplar of such a system representation is given for firm industry equilibrium. We demonstrate the traditional ML methodology in the economics context and leverage firm financial data to explore a frontier concept known as behavioral heterogeneity. Behavioral heterogeneity on the firm level can be imagined as a firm's interactions with different types of Economic entities over time. These interactions could impose varying degrees of institutional constraints on a firm's business behavior. We specifically look at behavioral
Haschke, J M; Siekhaus, W J
2009-02-11
Static concentrations of plutonium oxidation states in solution and at surfaces in oxide-water systems are identified as non-equilibrium steady states. These kinetically controlled systems are described by redox cycles based on irreversible disproportionation of Pu(IV), Pu(V), and Pu(VI) in OH-bridged intermediate complexes and at OH-covered oxide surfaces. Steady state is fixed by continuous redox cycles driven by radioactivity-promoted electron-transfer and energetically favorable reactions of Pu(III) and Pu(VII) disproportionation products with H2O. A model based on the redox cycles accounts for the high steady-state [Pu] coexisting with Pu(IV) hydrous oxide at pH 0-15 and for predominance of Pu(V) and Pu(VI) in solution. The steady-state [Pu] depends on pH and the surface area of oxide in solution, but not on the initial Pu oxidation state. PuO{sub 2+x} formation is attributed to high Pu(V) concentrations existing at water-exposed oxide surfaces. Results infer that migration of Pu in an aqueous environment is controlled by kinetic factors unique to that site and that the predominant oxidation states in solution are Pu(V) and Pu(VI).
Model formulation of non-equilibrium gas radiation for hypersonic flight vehicles
NASA Technical Reports Server (NTRS)
Chang, Ing
1989-01-01
Several radiation models for low density nonequilibrium hypersonic flow are studied. It is proposed that these models should be tested by the 3-D VRFL code developed at NASA/JSC. A modified and optimized radiation model may be obtained from the testing. Then, the current VRFL code could be expanded to solve hypersonic flow problems with nonequilibrium thermal radiation.
High Order Well-Balanced Schemes and Applications to Non-Equilibrium Flow with Stiff Source Terms
Wang, W; Shu, C; Yee, H C; Sjogreen, B
2009-01-14
The stiffness of the source terms in modeling non-equilibrium flow problems containing finite-rate chemistry or combustion poses additional numerical difficulties beyond that for solving non-reacting flows. A well-balanced scheme, which can preserve certain non-trivial steady state solutions exactly, may help to resolve some of these difficulties. In this paper, a simple one dimensional non-equilibrium model with one temperature is considered. We first describe a general strategy to design high order well-balanced finite difference schemes and then study the well-balanced properties of high order finite difference weighted essentially non-oscillatory (WENO) scheme, modified balanced WENO schemes and various TVD schemes. The advantages of using a well-balanced scheme in preserving steady states and in resolving small perturbations of such states will be shown. Additional numerical examples are provided to verify the good resolution, in addition to the well-balancedness, for both smooth and discontinuous solutions as well.
Visser, P. J. de; Yates, S. J. C.; Guruswamy, T.; Goldie, D. J.; Withington, S.; Neto, A.; Llombart, N.; Baryshev, A. M.; Klapwijk, T. M.; Baselmans, J. J. A.
2015-06-22
We have measured the absorption of terahertz radiation in a BCS superconductor over a broad range of frequencies from 200 GHz to 1.1 THz, using a broadband antenna-lens system and a tantalum microwave resonator. From low frequencies, the response of the resonator rises rapidly to a maximum at the gap edge of the superconductor. From there on, the response drops to half the maximum response at twice the pair-breaking energy. At higher frequencies, the response rises again due to trapping of pair-breaking phonons in the superconductor. In practice, this is a measurement of the frequency dependence of the quasiparticle creation efficiency due to pair-breaking in a superconductor. The efficiency, calculated from the different non-equilibrium quasiparticle distribution functions at each frequency, is in agreement with the measurements.
NASA Technical Reports Server (NTRS)
Whiting, Ellis E.
1990-01-01
Future space vehicles returning from distant missions or high earth orbits may enter the upper regions of the atmosphere and use aerodynamic drag to reduce their velocity before they skip out of the atmosphere and enter low earth orbit. The Aeroassist Flight Experiment (AFE) is designed to explore the special problems encountered in such entries. A computer code was developed to calculate the radiative transport along line-or-sight in the general 3-D flow field about an arbitrary entry vehicle, if the temperatures and species concentrations along the line-of-sight are known. The radiative heating calculation at the stagnation point of the AFE vehicle along the entry trajectory was performed, including a detailed line-by-line accounting of the radiative transport in the vacuum ultraviolet (below 200 nm) by the atomic N and O lines. A method was developed for making measurements of the haze particles in the Titan atmosphere above 200 km altitude. Several other tasks of a continuing nature, to improve the technical ability to calculate the nonequilibrium gas dynamic flow field and radiative heating of entry vehicles, were completed or advanced.
Non-equilibrium radiation during SiC-CO2 plasma interaction
NASA Astrophysics Data System (ADS)
Brémare, Noémie; Jouen, Samuel; Boubert, Pascal
2016-04-01
The radiation of a pure CO2 inductive plasma was recorded between 190 and 920 nm during its interaction with a SiC sample under a pressure equal to 6 kPa and an estimated global specific enthalpy close to 12 MJ kg-1. The plasma electronic excitation was found to be out of equilibrium. The main radiators were found to be O, C, C2 and, mainly, CO. The radiation is especially significant where the plasma chemically interacts with the material revealing a stronger electronic excitation close to the surface. Excitation temperatures were also found to increase in the chemical boundary layer, which is four times smaller than the thermal boundary layer. This raises questions about the energy exchange processes of the excited states and about chemical behaviour independent of their respective ground states. The surface is found to be covered by an inhomogeneous silica layer revealing a passive oxidation, but also by bubble structures, indicative of the transition towards active oxidation. The surface temperature is estimated to be 1800-1900 K. Raman spectroscopy measurements on the surface and optical spectroscopy measurements in the boundary layer provide proof of carbon production coming from the SiC.
Energy deposition and non-equilibrium infared radiation of energetic auroral electrons
NASA Astrophysics Data System (ADS)
Wu, Yadong; Gao, Bo; Zhu, Guangsheng; Li, Ziguang
2016-07-01
Infrared radiation caused by energetic auroral electrons plays an important role in the thermospheric hear budget, and may be seen as background by infrared surveillance sensors. The auroral electron deposition leads to the ionization, excitation, and dissociation of neutral species(N2,O2,and O), and initiates a series of chemical reaction in the upper atmosphere, finally causes the optical emission of infared excited emitters. In this study, the whole progress from the initial auroral electrons energy deposition to the final infrared emissions has been modeled, which including space plasma, atmospheric physical chemistry, and radiative transfer. The initial atmosphere parameters before auroral disturbing are given by MSIS00 model. The primary electron flux at the top of atmosphere is given by a statistical fitting with the sum of three distribution terms, a power law, a Maxwellian and a Guassian. A semi-emprical model is used in the calculation of energy depositon of single primary electron. The total integral ion pairs production rate is obtained after combining with the initial primary electron flux. The production rate and flux of secondary electrons are modeled with a continuous slow down approximation, using different excitation, ionization, dissociation cross sections of N2, O2, and O to electrons. The photochemical reactions with auroral disturbance is analysed, and its calculation model is established. A "three-step" calculation method is created to obtain number densities of eleven species in the hight between 90-160 km, which containing N2+, O2+, O+, O2+(a4Π), O+(2D), O+(2P), N2(A3Σ), N(2D), N(4S), NO+, and N+. Number densities of different vibraional levels of NO and NO+ are got with steady state assumption, considering 1-12 vibrational levels of NO and 1-14 vibrational levels of NO+. The infared emissions and the spectral lines of the two radiating bodies are calculated with a fuzzy model of spectral band.
Modeling of non-equilibrium phenomena in expanding flows by means of a collisional-radiative model
Munafò, A.; Lani, A.; Bultel, A.; Panesi, M.
2013-07-15
The effects of non-equilibrium in a quasi-one-dimensional nozzle flow are investigated by means of a collisional-radiative model. The gas undergoing the expansion is an air plasma and consists of atoms, molecules, and free electrons. In the present analysis, the electronic excited states of atomic and molecular species are treated as separate pseudo-species. Rotational and vibrational energy modes are assumed to be populated according to Boltzmann distributions. The coupling between radiation and gas dynamics is accounted for, in simplified manner, by using escape factors. The flow governing equations for the steady quasi-one-dimensional flow are written in conservative form and discretized in space by means of a finite volume method. Steady-state solutions are obtained by using a fully implicit time integration scheme. The analysis of the evolution of the electronic distribution functions reveals a substantial over-population of the high-lying excited levels of atoms and molecules in correspondence of the nozzle exit. The influence of optical thickness is also studied. The results clearly demonstrate that the radiative transitions, within the optically thin approximation, drastically reduce the over-population of high-lying electronic levels.
NASA Technical Reports Server (NTRS)
Meyer, Scott A.; Bershader, Daniel; Sharma, Surendra P.; Deiwert, George S.
1996-01-01
Absorption measurements with a tunable vacuum ultraviolet light source have been proposed as a concentration diagnostic for atomic oxygen, and the viability of this technique is assessed in light of recent measurements. The instrumentation, as well as initial calibration measurements, have been reported previously. We report here additional calibration measurements performed to study the resonance broadening line shape for atomic oxygen. The application of this diagnostic is evaluated by considering the range of suitable test conditions and requirements, and by identifying issues that remain to be addressed.
Non-equilibrium degassing and a primordial source for helium in ocean-island volcanism.
Gonnermann, Helge M; Mukhopadhyay, Sujoy
2007-10-25
Radioactive decay of uranium and thorium produces 4He, whereas 3He in the Earth's mantle is not produced by radioactive decay and was only incorporated during accretion-that is, it is primordial. 3He/4He ratios in many ocean-island basalts (OIBs) that erupt at hotspot volcanoes, such as Hawaii and Iceland, can be up to sixfold higher than in mid-ocean ridge basalts (MORBs). This is inferred to be the result of outgassing by melt production at mid-ocean ridges in conjunction with radiogenic ingrowth of 4He, which has led to a volatile-depleted upper mantle (MORB source) with low 3He concentrations and low 3He/4He ratios. Consequently, high 3He/4He ratios in OIBs are conventionally viewed as evidence for an undegassed, primitive mantle source, which is sampled by hot, buoyantly upwelling deep-mantle plumes. However, this conventional model provides no viable explanation of why helium concentrations and elemental ratios of He/Ne and He/Ar in OIBs are an order of magnitude lower than in MORBs. This has been described as the 'helium concentration paradox' and has contributed to a long-standing controversy about the structure and dynamics of the Earth's mantle. Here we show that the helium concentration paradox, as well as the full range of noble-gas concentrations observed in MORB and OIB glasses, can self-consistently be explained by disequilibrium open-system degassing of the erupting magma. We show that a higher CO2 content in OIBs than in MORBs leads to more extensive degassing of helium in OIB magmas and that noble gases in OIB lavas can be derived from a largely undegassed primitive mantle source.
NASA Astrophysics Data System (ADS)
Hashizume, Hiroshi; Ohta, Takayuki; Fengdong, Jia; Takeda, Keigo; Ishikawa, Kenji; Hori, Masaru; Ito, Masafumi
2013-10-01
The effectiveness of atomic and excited molecular oxygen species at inactivating Penicillium digitatum spores was quantitatively investigated by measuring these species and evaluating the spore inactivation rate. To avoid the effects of ultraviolet light and charged species, a non-equilibrium atmospheric-pressure radical source, which supplies only neutral radicals, was employed. Ground-state atomic oxygen (O(3Pj)) and excited molecular oxygen (O2(1Δg)) species were measured using vacuum ultraviolet absorption spectroscopy. The inactivation rate of spores was evaluated using the colony count method. The lifetimes of O(3Pj) and O2(1Δg) in an argon gas ambient at atmospheric pressure were found to be about 0.5 ms and much more than tens of ms, and their spore inactivation rates were about 10-17 cm3 s-1 and much lower than 10-21 cm3 s-1, respectively.
NASA Astrophysics Data System (ADS)
Abourabia, Aly Maher; Wahid, Taha Zakaraia Abdel
2011-05-01
A new approach for studying the influence of a thermal radiation field upon a rarefied neutral gas is introduced. We insert the radiation field effect in the force term of the Boltzmann equation. In a frame co-moving with the fluid, the BGK (Bhatnager-Gross-Krook) model kinetic equation is applied analytically. The one-dimensional steady problem is studied using the Liu-Lees model. We apply the moment method to follow the behavior of the macroscopic properties of the gas, such as the temperature and concentration. They are substituted into the corresponding two-stream Maxwellian distribution functions, permitting the investigation of the non-equilibrium thermodynamic properties of the system (gas + heated plate). The entropy, entropy flux, entropy production, thermodynamic forces and the kinetic coefficients are obtained. We verify the celebrated Onsager reciprocity relations for the system. The ratios between the different contributions of the internal energy changes based upon the total derivatives of the extensive parameters are estimated via the Gibbs formula. The results are applied to the Helium gas for various radiation field intensities due to different plate temperatures. Figures illustrating the calculated variables are drawn to predict their behavior and the results are discussed.
Brucer, M.H.
1958-04-15
A novel long-lived source of gamma radiation especially suitable for calibration purposes is described. The source of gamma radiation is denoted mock iodine131, which comprises a naixture of barium-133 and cesium-137. The barium and cesium are present in a barium-cesium ratio of approximately 5.7/1 to 14/1, uniformly dispersed in an ion exchange resin and a filter surrounding the resin comprised of a material of atomic number below approximately 51, and substantially 0.7 to 0.9 millimeter thick.
Non-equilibrium phase transitions
Mottola, E.; Cooper, F.M.; Bishop, A.R.; Habib, S.; Kluger, Y.; Jensen, N.G.
1998-12-31
This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Non-equilibrium phase transitions play a central role in a very broad range of scientific areas, ranging from nuclear, particle, and astrophysics to condensed matter physics and the material and biological sciences. The aim of this project was to explore the path to a deeper and more fundamental understanding of the common physical principles underlying the complex real time dynamics of phase transitions. The main emphasis was on the development of general theoretical tools to deal with non-equilibrium processes, and of numerical methods robust enough to capture the time-evolving structures that occur in actual experimental situations. Specific applications to Laboratory multidivisional efforts in relativistic heavy-ion physics (transition to a new phase of nuclear matter consisting of a quark-gluon plasma) and layered high-temperature superconductors (critical currents and flux flow at the National High Magnetic Field Laboratory) were undertaken.
Open problems in non-equilibrium physics
Kusnezov, D.
1997-09-22
The report contains viewgraphs on the following: approaches to non-equilibrium statistical mechanics; classical and quantum processes in chaotic environments; classical fields in non-equilibrium situations: real time dynamics at finite temperature; and phase transitions in non-equilibrium conditions.
Non-equilibrium quantum heat machines
NASA Astrophysics Data System (ADS)
Alicki, Robert; Gelbwaser-Klimovsky, David
2015-11-01
Standard heat machines (engine, heat pump, refrigerator) are composed of a system (working fluid) coupled to at least two equilibrium baths at different temperatures and periodically driven by an external device (piston or rotor) sometimes called the work reservoir. The aim of this paper is to go beyond this scheme by considering environments which are stationary but cannot be decomposed into a few baths at thermal equilibrium. Such situations are important, for example in solar cells, chemical machines in biology, various realizations of laser cooling or nanoscopic machines driven by laser radiation. We classify non-equilibrium baths depending on their thermodynamic behavior and show that the efficiency of heat machines powered by them is limited by the generalized Carnot bound.
Thode, Lester E.
1981-01-01
A device and method for relativistic electron beam heating of a high-density plasma in a small localized region. A relativistic electron beam generator or accelerator produces a high-voltage electron beam which propagates along a vacuum drift tube and is modulated to initiate electron bunching within the beam. The beam is then directed through a low-density gas chamber which provides isolation between the vacuum modulator and the relativistic electron beam target. The relativistic beam is then applied to a high-density target plasma which typically comprises DT, DD, or similar thermonuclear gas at a density of 10.sup.17 to 10.sup.20 electrons per cubic centimeter. The target gas is ionized prior to application of the relativistic electron beam by means of a laser or other preionization source to form a plasma. Utilizing a relativistic electron beam with an individual particle energy exceeding 3 MeV, classical scattering by relativistic electrons passing through isolation foils is negligible. As a result, relativistic streaming instabilities are initiated within the high-density target plasma causing the relativistic electron beam to efficiently deposit its energy into a small localized region of the high-density plasma target.
Non-equilibrium Kinematics in Merging Galaxies
NASA Astrophysics Data System (ADS)
Mihos, J. C.
Measurements of the kinematics of merging galaxies are often used to derive dynamical masses, study evolution onto the fundamental plane, or probe relaxation processes. These measurements are often compromised to some degree by strong non-equilibrium motions in the merging galaxies. This talk focuses on the evolution of the kinematics of merging galaxies, and highlights some pitfalls which occur when studying non-equilibrium systems.
New non-equilibrium matrix imbibition equation for double porosity model
NASA Astrophysics Data System (ADS)
Konyukhov, Andrey; Pankratov, Leonid
2016-07-01
The paper deals with the global Kondaurov double porosity model describing a non-equilibrium two-phase immiscible flow in fractured-porous reservoirs when non-equilibrium phenomena occur in the matrix blocks, only. In a mathematically rigorous way, we show that the homogenized model can be represented by usual equations of two-phase incompressible immiscible flow, except for the addition of two source terms calculated by a solution to a local problem being a boundary value problem for a non-equilibrium imbibition equation given in terms of the real saturation and a non-equilibrium parameter.
Sauer, M.C. Jr.
1981-01-01
Characteristics of various sources of pulsed radiation are examined from the viewpoint of their importance to the radiation chemist, and some examples of uses of such sources are mentioned. A summary is given of the application of methods of physical dosimetry to pulsed sources, and the calibration of convenient chemical dosimeters by physical dosimetry is outlined. 7 figures, 1 table.
NASA Astrophysics Data System (ADS)
Seoane, N.; Martinez, A.
2013-09-01
In this paper we present a 3D quantum transport simulation study of source-to-drain tunnelling in gate-all-around Si nanowire transistors by using the non-equilibrium Green's function approach. The impact of the channel length, device cross-section, and drain and gate applied biases on the source-to-drain tunnelling is examined in detail. The overall effect of tunnelling on the ID-VG characteristics is also investigated. Tunnelling in devices with channel lengths of 10 nm or less substantially enhances the off-current. This enhancement is more important at high drain biases and at larger cross-sections where the sub-threshold slope is substantially degraded. A less common effect is the increase in the on-current due to the tunnelling which contributes as much as 30% of the total on-current. This effect is almost independent of the cross-section, and it depends weakly on the studied channel lengths.
Radiation Source Replacement Workshop
Griffin, Jeffrey W.; Moran, Traci L.; Bond, Leonard J.
2010-12-01
This report summarizes a Radiation Source Replacement Workshop in Houston Texas on October 27-28, 2010, which provided a forum for industry and researchers to exchange information and to discuss the issues relating to replacement of AmBe, and potentially other isotope sources used in well logging.
Radiation source search toolkit
NASA Astrophysics Data System (ADS)
Young, Jason S.
The newly developed Radiation Source Search Toolkit (RSST) is a toolkit for generating gamma-ray spectroscopy data for use in the testing of source search algorithms. RSST is designed in a modular fashion to allow for ease of use while still maintaining accuracy in developing the output spectra. Users are allowed to define a real-world path for mobile radiation detectors to travel as well as radiation sources for possible detection. RSST can accept measured or simulated radiation spectrum data for generation into a source search simulation. RSST handles traversing the path, computing distance related attenuation, and generating the final output spectra. RSST also has the ability to simulate anisotropic shielding as well as traffic conditions that would impede a ground-based detection platform in a real-world scenario. RSST provides a novel fusion between spectral data and geospatial source search data generation. By utilizing the RSST, researchers can easily generate multiple datasets for testing detection algorithms without the need for actual radiation sources and mobile detector platforms.
NASA Technical Reports Server (NTRS)
Levine, H.
1980-01-01
The power output from given sources is usually ascertained via an energy flux integral over the normal directions to a remote (far field) surface; an alternative procedure, which utilizes an integral that specifies the direct rate of working by the source on the resultant field, is described and illustrated for both point and continuous source distribution. A comparison between the respective procedures is made in the analysis of sound radiated from a periodic dipole source whose axis performs a periodic plane angular movement about a fixed direction. Thus, adopting a conventional approach, Sretenskii (1956) characterizes the rotating dipole in terms of an infinite number of stationary ones along a pari of orthogonal directions in the plane, and through the far field representation of the latter, arrives at a series development for the instantaneous radiated power, whereas the local manner of power calculation dispenses with the equivalent infinite aggregate of sources and yields a compact analytical result.
Non-equilibrium Dynamics of DNA Nanotubes
NASA Astrophysics Data System (ADS)
Hariadi, Rizal Fajar
Can the fundamental processes that underlie molecular biology be understood and simulated by DNA nanotechnology? The early development of DNA nanotechnology by Ned Seeman was driven by the desire to find a solution to the protein crystallization problem. Much of the later development of the field was also driven by envisioned applications in computing and nanofabrication. While the DNA nanotechnology community has assembled a versatile tool kit with which DNA nanostructures of considerable complexity can be assembled, the application of this tool kit to other areas of science and technology is still in its infancy. This dissertation reports on the construction of non-equilibrium DNA nanotube dynamic to probe molecular processes in the areas of hydrodynamics and cytoskeletal behavior. As the first example, we used DNA nanotubes as a molecular probe for elongational flow measurement in different micro-scale flow settings. The hydrodynamic flow in the vicinity of simple geometrical objects, such as a rigid DNA nanotube, is amenable to rigorous theoretical investigation. We measured the distribution of elongational flows produced in progressively more complex settings, ranging from the vicinity of an orifice in a microfluidic chamber to within a bursting bubble of Pacific ocean water. This information can be used to constrain theories on the origin of life in which replication involves a hydrodynamically driven fission process, such as the coacervate fission proposed by Oparin. A second theme of this dissertation is the bottom-up construction of a de novo artificial cytoskeleton with DNA nanotubes. The work reported here encompasses structural, locomotion, and control aspects of non-equilibrium cytoskeletal behavior. We first measured the kinetic parameters of DNA nanotube assembly and tested the accuracy of the existing polymerization models in the literature. Toward recapitulation of non-equilibrium cytoskeletal dynamics, we coupled the polymerization of DNA
Non-Equilibrium Transitions of Heliospheric plasma
NASA Astrophysics Data System (ADS)
Livadiotis, G.; McComas, D. J.
2011-12-01
Recent advances in Space Physics theory have established the connection between non-extensive Statistical Mechanics and space plasmas by providing a theoretical basis for the empirically derived kappa distributions commonly used to describe the phase space distribution functions of these systems [1]. The non-equilibrium temperature and the kappa index that govern these distributions are the two independent controlling parameters of non-equilibrium systems [1-3]. The significance of the kappa index is primarily given by its role in identifying the non-equilibrium stationary states, and measuring their "thermodynamic distance" from thermal equilibrium [4], while its physical meaning is connected to the correlation between the system's particles [5]. For example, analysis of the IBEX high Energetic Neutral Atom spectra [6] showed that the vast majority of measured kappa indices are between ~1.5 and ~2.5, consistent with the far-equilibrium "cavity" of minimum entropy discovered by Livadiotis & McComas [2]. Spontaneous procedures that can increase the entropy, move the system gradually toward equilibrium, that is the state with the maximum (infinite) kappa index. Other external factors that may decrease the entropy, move the system back to states further from equilibrium where the kappa indices are smaller. Newly formed pick-up ions can play this critical role in the solar wind and other space plasmas. We have analytically shown that their highly ordered motion can reduce the average entropy in the plasma beyond the termination shock, inside the inner heliosheath [7]. Non-equilibrium transitions have a key role in understanding the governing thermodynamical processes of space plasmas. References 1. Livadiotis, G., & McComas, D. J. 2009, JGR, 114, 11105. 2. Livadiotis, G., & McComas, D. J. 2010a, ApJ, 714, 971. 3. Livadiotis, G., & McComas, D. J. 2010c, in AIP Conf. Proc. 9, Pickup Ions Throughout the Heliosphere and Beyond, ed. J. LeRoux, V. Florinski, G. P. Zank, & A
Non-equilibrium many body dynamics
Creutz, M.; Gyulassy, M.
1997-09-22
This Riken BNL Research Center Symposium on Non-Equilibrium Many Body Physics was held on September 23-25, 1997 as part of the official opening ceremony of the Center at Brookhaven National Lab. A major objective of theoretical work at the center is to elaborate on the full spectrum of strong interaction physics based on QCD, including the physics of confinement and chiral symmetry breaking, the parton structure of hadrons and nuclei, and the phenomenology of ultra-relativistic nuclear collisions related to the up-coming experiments at RHIC. The opportunities and challenges of nuclear and particle physics in this area naturally involve aspects of the many body problem common to many other fields. The aim of this symposium was to find common theoretical threads in the area of non-equilibrium physics and modern transport theories. The program consisted of invited talks on a variety topics from the fields of atomic, condensed matter, plasma, astrophysics, cosmology, and chemistry, in addition to nuclear and particle physics. Separate abstracts have been indexed into the database for contributions to this workshop.
Turbulence modeling for non-equilibrium flow
NASA Technical Reports Server (NTRS)
Durbin, P. A.
1995-01-01
The work performed during this year has involved further assessment and extension of the k-epsilon-v(exp 2) model, and initiation of work on scalar transport. The latter is introduced by the contribution of Y. Shabany to this volume. Flexible, computationally tractable models are needed for engineering CFD. As computational technology has progressed, the ability and need to use elaborate turbulence closure models has increased. The objective of our work is to explore and develop new analytical frameworks that might extend the applicability of the modeling techniques. In past years the development of a method for near-wall modeling was described. The method has been implemented into a CFD code and its viability has been demonstrated by various test cases. Further tests are reported herein. Non-equilibrium near-wall models are needed for some heat transfer applications. Scalar transport seems generally to be more sensitive to non-equilibrium effects than is momentum transport. For some applications turbulence anisotropy plays a role and an estimate of the full Reynolds stress tensor is needed. We have begun work on scalar transport per se, but in this brief I will only report on an extension of the k-epsilon-v(exp 2) model to predict the Reynolds stress tensor.
In command of non-equilibrium.
Roduner, Emil; Radhakrishnan, Shankara Gayathri
2016-05-21
The second law of thermodynamics is well known for determining the direction of spontaneous processes in the laboratory, life and the universe. It is therefore often called the arrow of time. Less often discussed but just as important is the effect of kinetic barriers which intercept equilibration and preserve highly ordered, high energy non-equilibrium states. Examples of such states are many modern materials produced intentionally for technological applications. Furthermore, all living organisms fuelled directly by photosynthesis and those fuelled indirectly by living on high energy nutrition represent preserved non-equilibrium states. The formation of these states represents the local reversal of the arrow of time which only seemingly violates the second law. It has been known since the seminal work of Prigogine that the stabilisation of these states inevitably requires the dissipation of energy in the form of waste heat. It is this feature of waste heat dissipation following the input of energy that drives all processes occurring at a non-zero rate. Photosynthesis, replication of living organisms, self-assembly, crystal shape engineering and distillation have this principle in common with the well-known Carnot cycle in the heat engine. Drawing on this analogy, we subsume these essential and often sophisticated driven processes under the term machinery of life. PMID:27146424
Synchrotron radiation sources and research
Teng, L.C.
1995-12-31
This is an introduction and a review of Synchrotron Radiation sources and the research performed using synchrotron radiation. I will begin with a brief discussion of the two principal uses of particle storage rings: for colliding beams (Collider) and for synchrotron radiation (Radiator). Then I will concentrate on discussions of synchrotron radiation topics, starting with a historical account, followed by descriptions of the features of the storage ring and the features of the radiation from the simplest source -- the bending magnet. I will then discuss the special insertion device sources -- wigglers and undulators -- and their radiations, and end with a brief general account of the research and other applications of synchrotron radiation.
Non-equilibrium Helium Ionization in an MHD Simulation of the Solar Atmosphere
NASA Astrophysics Data System (ADS)
Golding, Thomas Peter; Leenaarts, Jorrit; Carlsson, Mats
2016-02-01
The ionization state of the gas in the dynamic solar chromosphere can depart strongly from the instantaneous statistical equilibrium commonly assumed in numerical modeling. We improve on earlier simulations of the solar atmosphere that only included non-equilibrium hydrogen ionization by performing a 2D radiation-magnetohydrodynamics simulation featuring non-equilibrium ionization of both hydrogen and helium. The simulation includes the effect of hydrogen Lyα and the EUV radiation from the corona on the ionization and heating of the atmosphere. Details on code implementation are given. We obtain helium ion fractions that are far from their equilibrium values. Comparison with models with local thermodynamic equilibrium (LTE) ionization shows that non-equilibrium helium ionization leads to higher temperatures in wavefronts and lower temperatures in the gas between shocks. Assuming LTE ionization results in a thermostat-like behavior with matter accumulating around the temperatures where the LTE ionization fractions change rapidly. Comparison of DEM curves computed from our models shows that non-equilibrium ionization leads to more radiating material in the temperature range 11-18 kK, compared to models with LTE helium ionization. We conclude that non-equilibrium helium ionization is important for the dynamics and thermal structure of the upper chromosphere and transition region. It might also help resolve the problem that intensities of chromospheric lines computed from current models are smaller than those observed.
Non-equilibrium calcium ionisation in the solar atmosphere
NASA Astrophysics Data System (ADS)
Wedemeyer-Böhm, S.; Carlsson, M.
2011-04-01
Context. The chromosphere of the Sun is a temporally and spatially very varying medium for which the assumption of ionisation equilibrium is questionable. Aims: Our aim is to determine the dominant processes and timescales for the ionisation equilibrium of calcium under solar chromospheric conditions. Methods: The study is based on numerical simulations with the RADYN code, which combines hydrodynamics with a detailed solution of the radiative transfer equation. The calculations include a detailed non-equilibrium treatment of hydrogen, calcium, and helium. Next to an hour long simulation sequence, additional simulations are produced, for which the stratification is slightly perturbed so that a ionisation relaxation timescale can be determined. The simulations are characterised by upwards propagating shock waves, which cause strong temperature fluctuations and variations of the (non-equilibrium) ionisation degree of calcium. Results: The passage of a hot shock front leads to a strong net ionisation of Ca II, rapidly followed by net recombination. The relaxation timescale of the calcium ionisation state is found to be of the order of a few seconds at the top of the photosphere and 10 to 30 s in the upper chromosphere. At heights around 1 Mm, we find typical values around 60 s and in extreme cases up to ~150 s. Generally, the timescales are significantly reduced in the wakes of ubiquitous hot shock fronts. The timescales can be reliably determined from a simple analysis of the eigenvalues of the transition rate matrix. The timescales are dominated by the radiative recombination from Ca III into the metastable Ca II energy levels of the 4d 2D term. These transitions depend strongly on the density of free electrons and therefore on the (non-equilibrium) ionisation degree of hydrogen, which is the main electron donor. Conclusions: The ionisation/recombination timescales derived here are too long for the assumption of an instantaneous ionisation equilibrium to be valid
Non-equilibrium diffusion combustion of a fuel droplet
NASA Astrophysics Data System (ADS)
Tyurenkova, Veronika V.
2012-06-01
A mathematical model for the non-equilibrium combustion of droplets in rocket engines is developed. This model allows to determine the divergence of combustion rate for the equilibrium and non-equilibrium model. Criterion for droplet combustion deviation from equilibrium is introduced. It grows decreasing droplet radius, accommodation coefficient, temperature and decreases on decreasing diffusion coefficient. Also divergence from equilibrium increases on reduction of droplet radius. Droplet burning time essentially increases under non-equilibrium conditions. Comparison of theoretical and experimental data shows that to have adequate solution for small droplets it is necessary to use the non-equilibrium model.
Spin-population inversion in magnetic point contacts under non-equilibrium conditions
NASA Astrophysics Data System (ADS)
Pietsch, Torsten; Egle, Stefan; Scheer, Elke
2012-02-01
The creation of a novel type of spin-based electronics is one of the most intensively researched topics in current solid-state physics. The unifying characteristics in this advancing field is that the spin degree of freedom of the electron rather than its charge is exploited to achieve a specific device functionality. Recently, theoretical predictions suggest that spin-inversion in metallic point contacts under strong non-equilibrium conditions may enable the design of novel types of radiation sources. These radiation sources are highly tunable and of giant intensity compared to cutting-edge semiconductor devices, due to the much larger electron density in metals. Moreover, the accessible frequency range covers both, microwave (GHz) and THz radiation. Especially the later one is of great interest, since up to date there is no miniaturized, high intensity THz source available. Therefore, the experimental demonstration of this lasing effect in metallic systems is an important breakthrough in solid state physics. Presently the concept of spin-flip lasing in magnetic point contacts rests on theoretical predictions and first proof of principle studies. Herein we present detailed investigations on the magneto-transport properties of magnetic herterostructures and -point contacts. In particular, we study the complex interplay between magnetization, current density and the influence of high frequency (GHz and THz) fields on the magneto-transport properties of magnetic point contacts. The results illustrate that a successful spin-population inversion can be detected via transport spectroscopy.
Future Synchrotron Radiation Sources
Winick, Herman
2003-07-09
Sources of synchrotron radiation (also called synchrotron light) and their associated research facilities have experienced a spectacular growth in number, performance, and breadth of application in the past two to three decades. In 1978 there were eleven electron storage rings used as light sources. Three of these were small rings, all below 500 mega-electron volts (MeV), dedicated to this purpose; the others, with energy up to 5 giga-electron volts (GeV), were used parasitically during the operation of the ring for high energy physics research. In addition, at that time synchrotron radiation from nine cyclic electron synchrotrons, with energy up to 5 GeV, was also used parasitically. At present no cyclic synchrotrons are used, while about 50 electron storage rings are in operation around the world as fully dedicated light sources for basic and applied research in a wide variety of fields. Among these fields are structural molecular biology, molecular environmental science, materials, analytic chemistry, microfabrication, archaeometry and medical diagnostics. These rings span electron energies from a few hundred MeV to 8 GeV. Several facilities serve 2000 or more users on 30-60 simultaneously operational experimental stations. The largest rings are more than 1 km in circumference, cost about US$1B to build and have annual budgets of about US$100M. This growth is due to the remarkable properties of synchrotron radiation, including its high intensity, brightness and stability; wide spectral range extending from the infra-red to hard x-rays; variable polarization; pulsed time structure; and high vacuum environment. The ever-expanding user community and the increasing number of applications are fueling a continued growth in the number of facilities around the world. In the past few years new types of light sources have been proposed based on linear accelerators. Linac-based sources now being pursued include the free-electron laser (FEL) and energy recovery linac (ERL
Non equilibrium electronic transport in multilayered nanostructures
NASA Astrophysics Data System (ADS)
Cruz-Rojas, Jesus
Recent advances in strongly correlated materials have produced systems with novel and interesting properties like high Tc superconductors, Mott insulators and others. These novel properties have sparked an interest in industry as well as in academia as new devices are being developed. One such kind of device that can be fabricated is a heterostructure, in which layers of different compounds are stacked in a single direction. Modern deposition techniques like electron beam epitaxy, in which atomic layers of different materials are deposited one at a time creating the device, are capable of fabricating heterostructures with atomic precision. We propose a technique to study heterostructures composed of strongly correlated materials out of equilibrium. By using the Keldysh Green's function formalism in the dynamical mean field theory (DMFT) framework the properties of a multilayered device are analyzed. The system is composed of infinite dimensional 2D lattices, stacked in the z direction. The first and last planes are then connected to a bulk reservoir, and several metallic planes are used to connect the bulk reservoir to the barrier region. The barrier region is the system of interest, also known as the device. The device is composed of a number of planes where the system correlations have been turned on. The correlations are then model by using the Falicov-Kimball Hamiltonian. The device is then connected to the bulk once again from the opposite side using metallic planes creating a symmetric system. In order to study the non equilibrium properties of the device a linear vector potential A(t) = A0 + tE is turned on a long time in the past for a unit of time and then turned off. This in turn will create a current in the bulk, in effect current biasing the device, as opposed to a voltage bias in which opposite sides of the device are held to a different potential. In this document we will explain the importance of the subject, we will derive and develop the algorithm
Nonlinear optics in non-equilibrium microplasmas
NASA Astrophysics Data System (ADS)
Compton, Ryan E.
2011-12-01
This dissertation details the nature of subnanosecond laser-induced microplasma dynamics, particularly concerning the evolution of the electron temperature and concentration. Central to this development is the advent of a femtosecond four-wave mixing (FWM) spectroscopic method. FWM (in the form of coherent anti-Stokes Raman scattering (CARS)) measurements are performed on the fundamental oxygen vibrational transition. An analytical expression is provided that accounts for the resonant and nonresonant contributions to the CARS signal generated from the interaction of broadband pump and Stokes pulses. The inherent phase mismatch is also accounted for, resulting in quantitative agreement between experiment and theory. FWM is then used to measure the early-time electron dynamics in the noble gas series from He to Xe following irradiation by an intense (1014 Wcm-2) nonresonant 80 fs laser pulse. An electron impact ionization cooling model is presented to determine the evolution of electron kinetic energies following ionization. Kinetic energies are predicted to evolve from > 20 eV to < 1 eV in the first 1.5 ns. The initial degree of ionization is determined experimentally via measurement of the Bremsstrahlung background emission, and modeled with a modified ADK theory based on tunnel ionization. Combined, these two descriptions account for the evolution of both the electron temperature and concentration and provide quantitative agreement with the FWM measurements. The model is further tested with measurements of the gas pressure and pump laser intensity on the electron dynamics. The FWM experiments are concluded with a qualitative discussion of dissociative recombination dynamics occurring in molecular microplasmas. The microplasma environment is used as a source for the generation of two-level systems in the excited state manifold of atomic oxygen and argon. These two-level systems are coupled using moderately intense ˜1 ps near-infrared (and near-resonant) pulses
Electrolytes: transport properties and non-equilibrium thermodynamics
Miller, D.G.
1980-12-01
This paper presents a review on the application of non-equilibrium thermodynamics to transport in electrolyte solutions, and some recent experimental work and results for mutual diffusion in electrolyte solutions.
Statistical physics of shear flow: a non-equilibrium problem
NASA Astrophysics Data System (ADS)
Evans, R. M. L.
2010-09-01
Complex fluids are easily and reproducibly driven into non-equilibrium steady states by the action of shear flow. The statistics of the microstructure of non-equilibrium fluids is important to the material properties of every complex fluid that flows, e.g. axle grease on a rotating bearing; blood circulating in capillaries; molten plastic flowing into a mould; the non-equilibrium onion phase of amphiphiles used for drug delivery; the list is endless. Such states are as diverse and interesting as equilibrium states, but are not governed by the same statistics as equilibrium materials. I review some recently discovered principles governing the probabilities of various types of molecular re-arrangements taking place within a sheared fluid. As well as providing new foundations for the study of non-equilibrium matter, the principles are applied to some simple models of particles interacting under flow, showing that the theory exhibits physically convincing behaviour.
Observing Organic Molecules in Interstellar Gases: Non Equilibrium Excitation.
NASA Astrophysics Data System (ADS)
Wiesenfeld, Laurent; Faure, Alexandre; Remijan, Anthony; Szalewicz, Krzysztof
2014-06-01
In order to observe quantitatively organic molecules in interstellar gas, it is necessary to understand the relative importance of photonic and collisional excitations. In order to do so, collisional excitation transfer rates have to be computed. We undertook several such studies, in particular for H_2CO and HCOOCH_3. Both species are observed in many astrochemical environments, including star-forming regions. We found that those two molecules behave in their low-lying rotational levels in an opposite way. For cis methyl-formate, a non-equilibrium radiative transfer treatment of rotational lines is performed, using a new set of theoretical collisional rate coefficients. These coefficients have been computed in the temperature range 5 to 30 K by combining coupled-channel scattering calculations with a high accuracy potential energy surface for HCOOCH_3 -- He. The results are compared to observations toward the Sagittarius B2(N) molecular cloud. A total of 2080 low-lying transitions of methyl formate, with upper levels below 25 K, were treated. These lines are found to probe a cold (30 K), moderately dense (n ˜ 104 cm-3) interstellar gas. In addition, our calculations indicate that all detected emission lines with a frequency below 30 GHz are collisionally pumped weak masers amplifying the background of Sgr B2(N). This result demonstrates the generality of the inversion mechanism for the low-lying transitions of methyl formate. For formaldehyde, we performed a similar non-equilibrium treatment, with H_2 as the collisional partner, thanks to the accurate H_2CO - H_2 potential energy surface . We found very different energy transfer rates for collisions with para-H_2 (J=0) and ortho-H_2 (J=1). The well-known absorption against the cosmological background of the 111→ 101 line is shown to depend critically on the difference of behaviour between para and ortho-H_2, for a wide range of H_2 density. We thank the CNRS-PCMI French national program for continuous support
Non-equilibrium processes in interstellar molecules
NASA Technical Reports Server (NTRS)
Strelnitskiy, V. S.
1979-01-01
The types of nonequilibrium emission and absorption by interstellar molecules are summarized. The observed brightness emission temperatures of compact OH and H2O sources are discussed using the concept of maser amplification. A single thermodynamic approach was used in which masers and anti-masers are considered as heat engines for the theoretical interpretation of the cosmic maser and anti-maser phenomena. The requirements for different models of pumping are formulated and a classification is suggested for the mechanisms of pumping, according to the source and discharge of energy.
Compton Sources of Electromagnetic Radiation
Geoffrey Krafft,Gerd Priebe
2011-01-01
When a relativistic electron beam interacts with a high-field laser beam, intense and highly collimated electromagnetic radiation will be generated through Compton scattering. Through relativistic upshifting and the relativistic Doppler effect, highly energetic polarized photons are radiated along the electron beam motion when the electrons interact with the laser light. For example, X-ray radiation can be obtained when optical lasers are scattered from electrons of tens-of-MeV beam energy. Because of the desirable properties of the radiation produced, many groups around the world have been designing, building, and utilizing Compton sources for a wide variety of purposes. In this review article, we discuss the generation and properties of the scattered radiation, the types of Compton source devices that have been constructed to date, and the prospects of radiation sources of this general type. Due to the possibilities of producing hard electromagnetic radiation in a device that is small compared to the alternative storage ring sources, it is foreseen that large numbers of such sources may be constructed in the future.
Radiation source for helium magnetometers
NASA Technical Reports Server (NTRS)
Slocum, Robert E. (Inventor)
1991-01-01
A radiation source (12) for optical magnetometers (10) which use helium isotopes as the resonance element (30) includes an electronically pumped semiconductor laser (12) which produces a single narrow line of radiation which is frequency stabilized to the center frequency of the helium resonance line to be optically pumped. The frequency stabilization is accomplished using electronic feedback (34, 40, 42, 44) to control a current sources (20) thus eliminating the need for mechanical frequency tuning.
Non-Equilibrium Effects on Hypersonic Turbulent Boundary Layers
NASA Astrophysics Data System (ADS)
Kim, Pilbum
Understanding non-equilibrium effects of hypersonic turbulent boundary layers is essential in order to build cost efficient and reliable hypersonic vehicles. It is well known that non-equilibrium effects on the boundary layers are notable, but our understanding of the effects are limited. The overall goal of this study is to improve the understanding of non-equilibrium effects on hypersonic turbulent boundary layers. A new code has been developed for direct numerical simulations of spatially developing hypersonic turbulent boundary layers over a flat plate with finite-rate reactions. A fifth-order hybrid weighted essentially non-oscillatory scheme with a low dissipation finite-difference scheme is utilized in order to capture stiff gradients while resolving small motions in turbulent boundary layers. The code has been validated by qualitative and quantitative comparisons of two different simulations of a non-equilibrium flow and a spatially developing turbulent boundary layer. With the validated code, direct numerical simulations of four different hypersonic turbulent boundary layers, perfect gas and non-equilibrium flows of pure oxygen and nitrogen, have been performed. In order to rule out uncertainties in comparisons, the same inlet conditions are imposed for each species, and then mean and turbulence statistics as well as near-wall turbulence structures are compared at a downstream location. Based on those comparisons, it is shown that there is no direct energy exchanges between internal and turbulent kinetic energies due to thermal and chemical non-equilibrium processes in the flow field. Instead, these non-equilibria affect turbulent boundary layers by changing the temperature without changing the main characteristics of near-wall turbulence structures. This change in the temperature induces the changes in the density and viscosity and the mean flow fields are then adjusted to satisfy the conservation laws. The perturbation fields are modified according to
Detection of Non-Equilibrium Fluctuations in Active Gels
NASA Astrophysics Data System (ADS)
Bacanu, Alexandru; Broedersz, Chase; Gladrow, Jannes; Mackintosh, Fred; Schmidt, Christoph; Fakhri, Nikta
Active force generation at the molecular scale in cells can result in stochastic non-equilibrium dynamics on mesoscpopic scales. Molecular motors such as myosin can drive steady-state stress fluctuations in cytoskeletal networks. Here, we present a non-invasive technique to probe non-equilibrium fluctuations in an active gel using single-walled carbon nanotubes (SWNTs). SWNTs are semiflexible polymers with intrinsic fluorescence in the near infrared. Both thermal and active motor-induced forces in the network induce transverse fluctuations of SWNTs. We demonstrate that active driven shape fluctuations of the SWNTs exhibit dynamics that reflect the non-equilibrium activity, in particular the emergence of correlations between the bending modes. We discuss the observation of breaking of detailed balance in this configurational space of the SWNT probes. Supported by National Defense Science and Engineering Graduate Student Fellowship (NDSEG).
The influence of non-equilibrium pressure on rotating flows
NASA Astrophysics Data System (ADS)
Zardadkhan, Irfan Rashid
This study was undertaken to investigate the influence of pressure relaxation on steady, incompressible flows with strong streamline curvature. In the early part of this dissertation research, the significance of non-equilibrium pressure forces in controlling the structure of a steady, two dimensional axial vortex was demonstrated. In order to extend the study of pressure relaxation influences on more complex rotating flows, this dissertation has examined other rotating flow features that can be associated with hurricanes, tornadoes and dust devils. To model these flows, modified boundary layer equations were developed for a fluid column rotating near a solid plane including the influence of non-equilibrium pressure forces. The far-field boundary conditions were inferred using the asymptotic behavior of the governing equations, and the boundary conditions for the axial and radial components of velocity were shown to be dependent on the pressure relaxation coefficient, η
Experimental approaches for studying non-equilibrium atmospheric plasma jets
Shashurin, A.; Keidar, M.
2015-12-15
This work reviews recent research efforts undertaken in the area non-equilibrium atmospheric plasma jets with special focus on experimental approaches. Physics of small non-equilibrium atmospheric plasma jets operating in kHz frequency range at powers around few Watts will be analyzed, including mechanism of breakdown, process of ionization front propagation, electrical coupling of the ionization front with the discharge electrodes, distributions of excited and ionized species, discharge current spreading, transient dynamics of various plasma parameters, etc. Experimental diagnostic approaches utilized in the field will be considered, including Rayleigh microwave scattering, Thomson laser scattering, electrostatic streamer scatterers, optical emission spectroscopy, fast photographing, etc.
DSMC predictions of non-equilibrium reaction rates.
Gallis, Michail A.; Bond, Ryan Bomar; Torczynski, John Robert
2010-04-01
A set of Direct Simulation Monte Carlo (DSMC) chemical-reaction models recently proposed by Bird and based solely on the collision energy and the vibrational energy levels of the species involved is applied to calculate nonequilibrium chemical-reaction rates for atmospheric reactions in hypersonic flows. The DSMC non-equilibrium model predictions are in good agreement with theoretical models and experimental measurements. The observed agreement provides strong evidence that modeling chemical reactions using only the collision energy and the vibrational energy levels provides an accurate method for predicting non-equilibrium chemical-reaction rates.
Radiation sources working group summary
Fazio, M.V.
1998-12-31
The Radiation Sources Working Group addressed advanced concepts for the generation of RF energy to power advanced accelerators. The focus of the working group included advanced sources and technologies above 17 GHz. The topics discussed included RF sources above 17 GHz, pulse compression techniques to achieve extreme peak power levels, components technology, technology limitations and physical limits, and other advanced concepts. RF sources included gyroklystrons, magnicons, free-electron masers, two beam accelerators, and gyroharmonic and traveling wave devices. Technology components discussed included advanced cathodes and electron guns, high temperature superconductors for producing magnetic fields, RF breakdown physics and mitigation, and phenomena that impact source design such as fatigue in resonant structures due to RF heating. New approaches for RF source diagnostics located internal to the source were discussed for detecting plasma and beam phenomena existing in high energy density electrodynamic systems in order to help elucidate the reasons for performance limitations.
Radiation source with shaped emission
Kubiak, Glenn D.; Sweatt, William C.
2003-05-13
Employing a source of radiation, such as an electric discharge source, that is equipped with a capillary region configured into some predetermined shape, such as an arc or slit, can significantly improve the amount of flux delivered to the lithographic wafers while maintaining high efficiency. The source is particularly suited for photolithography systems that employs a ringfield camera. The invention permits the condenser which delivers critical illumination to the reticle to be simplified from five or more reflective elements to a total of three or four reflective elements thereby increasing condenser efficiency. It maximizes the flux delivered and maintains a high coupling efficiency. This architecture couples EUV radiation from the discharge source into a ring field lithography camera.
Strongly Non-equilibrium Dynamics of Nanochannel Confined DNA
NASA Astrophysics Data System (ADS)
Reisner, Walter
Nanoconfined DNA exhibits a wide-range of fascinating transient and steady-state non-equilibrium phenomena. Yet, while experiment, simulation and scaling analytics are converging on a comprehensive picture regarding the equilibrium behavior of nanochannel confined DNA, non-equilibrium behavior remains largely unexplored. In particular, while the DNA extension along the nanochannel is the key observable in equilibrium experiments, in the non-equilibrium case it is necessary to measure and model not just the extension but the molecule's full time-dependent one-dimensional concentration profile. Here, we apply controlled compressive forces to a nanochannel confined molecule via a nanodozer assay, whereby an optically trapped bead is slid down the channel at a constant speed. Upon contact with the molecule, a propagating concentration ``shockwave'' develops near the bead and the molecule is dynamically compressed. This experiment, a single-molecule implementation of a macroscopic cylinder-piston apparatus, can be used to observe the molecule response over a range of forcings and benchmark theoretical description of non-equilibrium behavior. We show that the dynamic concentration profiles, including both transient and steady-state response, can be modelled via a partial differential evolution equation combining nonlinear diffusion and convection. Lastly, we present preliminary results for dynamic compression of multiple confined molecules to explore regimes of segregation and mixing for multiple chains in confinement.
Spacecraft Sterilization Using Non-Equilibrium Atmospheric Pressure Plasma
NASA Technical Reports Server (NTRS)
Cooper, Moogega; Vaze, Nachiket; Anderson, Shawn; Fridman, Gregory; Vasilets, Victor N.; Gutsol, Alexander; Tsapin, Alexander; Fridman, Alexander
2007-01-01
As a solution to chemically and thermally destructive sterilization methods currently used for spacecraft, non-equilibrium atmospheric pressure plasmas are used to treat surfaces inoculated with Bacillus subtilis and Deinococcus radiodurans. Evidence of significant morphological changes and reduction in viability due to plasma exposure will be presented, including a 4-log reduction of B. subtilis after 2 minutes of dielectric barrier discharge treatment.
Caloric and entropic temperatures in non-equilibrium steady states
NASA Astrophysics Data System (ADS)
Jou, D.; Restuccia, L.
2016-10-01
We examine the non-equilibrium consequences of two different definitions of temperature in systems out of equilibrium: one is based on the internal energy (caloric temperature), and the other one on the entropy (entropic temperature). We discuss the relation between the values obtained from these two definitions in ideal gases and in two-level systems.
Heat transfer in porous medium embedded with vertical plate: Non-equilibrium approach - Part A
NASA Astrophysics Data System (ADS)
Badruddin, Irfan Anjum; Quadir, G. A.
2016-06-01
Heat transfer in a porous medium embedded with vertical flat plate is investigated by using thermal non-equilibrium model. Darcy model is employed to simulate the flow inside porous medium. It is assumed that the heat transfer takes place by natural convection and radiation. The vertical plate is maintained at isothermal temperature. The governing partial differential equations are converted into non-dimensional form and solved numerically using finite element method. Results are presented in terms of isotherms and streamlines for various parameters such as heat transfer coefficient parameter, thermal conductivity ratio, and radiation parameter
Electron-Impact Excitation Cross Sections for Modeling Non-Equilibrium Gas
NASA Technical Reports Server (NTRS)
Huo, Winifred M.; Liu, Yen; Panesi, Marco; Munafo, Alessandro; Wray, Alan; Carbon, Duane F.
2015-01-01
In order to provide a database for modeling hypersonic entry in a partially ionized gas under non-equilibrium, the electron-impact excitation cross sections of atoms have been calculated using perturbation theory. The energy levels covered in the calculation are retrieved from the level list in the HyperRad code. The downstream flow-field is determined by solving a set of continuity equations for each component. The individual structure of each energy level is included. These equations are then complemented by the Euler system of equations. Finally, the radiation field is modeled by solving the radiative transfer equation.
Investigation of non-equilibrium electron-hole plasma in nanowires by THz spectroscopy
NASA Astrophysics Data System (ADS)
Cirlin, G. E.; Buyskih, A. C.; Bouravlev, A. D.; Samsonenko, Yu. B.; Kaliteevski, M. A.; Gallant, A. J.; Zeze, D.
2016-05-01
Efficient emission of THz radiation by AlGaAs nanowires via excitation of photocurrent by femtosecond optical pulses in nanowires was observed. Dynamics of photoinduced charge carrier was studied via influence of electron-hole plasma on THz radiation by optical pump THz probe method. It was found that characteristic time of screening of contact field is about 15 ps. Recombination of non-equilibrium occurs in two stages: fast recombination of free electron and holes (with relaxation time about 700 ps), and slow recombination (with relaxation time about 15 ns), which involves a capture of electrons and holes on the defects of crystalline structure of nanowires.
A non-equilibrium model for soil heating and evaporation under extreme conditions
NASA Astrophysics Data System (ADS)
Massman, W. J.
2014-12-01
Extreme heating of soils during fires can have long-term and irreversible consequences and given the increasing use of prescribed fire by land managers and the increasing probability of wildfires associated with global warming, one approach to improving understanding of these consequences is to better understand and model the dynamics of the coupled heat, (liquid) moisture, and vapor transport in soils during extreme heating events. The present study describes a model developed to simulate non-equilibrium soil evaporation and the transport of heat, moisture, and water vapor under conditions during fires where the surface heating of the soil often ranges between 10,000 and 100,000 Wm-2 for several minutes to several hours. The Hertz-Knudsen equation is the basis for constructing the model's non-equilibrium evaporative source term. Model performance is tested against laboratory measurements of soil temperature and moisture changes. Testing the present model with different formulations for soil hydraulic conductivity, water retention curve, water activity, and the non-equilibrium evaporative source term, indicates that virtually all the model's successes result from the use of a temperature dependent condensation coefficient in the evaporative source term, a rather surprising and unexpected result. On the other hand, the model solution is not a completely faithful representation of the laboratory data. Nevertheless, this new non-equilibrium model circumvents many of the problems that plagued an equilibrium model developed for the same purpose (Massman 2012: Water Resources Research 48, WR011710) and provides a much more physically realistic simulation than the earlier model. Finally, the present model should provide insight into modeling of heat and mass transport and evaporation, not only during high temperature and low moisture conditions, but for modeling these soil processes under less extreme environmental conditions as well.
Spectral Modeling in Astrophysics - The Physics of Non-equilibrium Clouds
NASA Astrophysics Data System (ADS)
Ferland, Gary; Williams, Robin
2016-02-01
Collisional-radiative spectral modeling plays a central role in astrophysics, probing phenomena ranging from the chemical evolution of the Universe to the energy production near supermassive black holes in distant quasars. The observed emission lines form in non-equilibrium clouds that have very low densities by laboratory standards, and are powered by energy sources which themselves are not in equilibrium. The spectrum is the result of a large number of microphysical processes, thermal statistics often do not apply, and analytical theory cannot be used. Numerical simulations are used to understand the physical state and the resulting spectrum. The greatest distinction between astrophysical modeling and conventional plasma simulations lies in the range of phenomena that must be considered. A single astronomical object will often have gas with kinetic temperatures of T˜10^6 K, 10^4 K, and T≤ 10^3 K, with the physical state ranging from molecular to fully ionized, and emitting over all wavelengths between the radio and x-ray. Besides atomic, plasma, and chemical physics, condensed matter physics is important because of the presence of small solid `grains' which affect the gas through catalytic reactions and the infrared emission they produce. The ionization, level populations, chemistry, and grain properties must be determined self-consistently, along with the radiation transport, to predict the observed spectrum. Although the challenge is great, so are the rewards. Numerical spectral simulations allow us to read the message contained in the spectrum emitted by objects far from the Earth that existed long ago.
Overview of terahertz radiation sources.
Gallerano, G. P.; Biedron, S. G.; Energy Systems; ENEA
2004-01-01
Although terahertz (THz) radiation was first observed about hundred years ago, the corresponding portion of the electromagnetic spectrum has been for long time considered a rather poorly explored region at the boundary between the microwaves and the infrared. This situation has changed during the past ten years with the rapid development of coherent THz sources, such as solid state oscillators, quantum cascade lasers, optically pumped solid state devices and novel free electron devices, which have in turn stimulated a wide variety of applications from material science to telecommunications, from biology to biomedicine. For a comprehensive review of THz technology the reader is addressed to a recent paper by P. Siegel. In this paper we focus on the development and perspectives of THz radiation sources.
Boltzmann equation solver adapted to emergent chemical non-equilibrium
Birrell, Jeremiah; Wilkening, Jon; Rafelski, Johann
2015-01-15
We present a novel method to solve the spatially homogeneous and isotropic relativistic Boltzmann equation. We employ a basis set of orthogonal polynomials dynamically adapted to allow for emergence of chemical non-equilibrium. Two time dependent parameters characterize the set of orthogonal polynomials, the effective temperature T(t) and phase space occupation factor ϒ(t). In this first paper we address (effectively) massless fermions and derive dynamical equations for T(t) and ϒ(t) such that the zeroth order term of the basis alone captures the particle number density and energy density of each particle distribution. We validate our method and illustrate the reduced computational cost and the ability to easily represent final state chemical non-equilibrium by studying a model problem that is motivated by the physics of the neutrino freeze-out processes in the early Universe, where the essential physical characteristics include reheating from another disappearing particle component (e{sup ±}-annihilation)
Evolution of specialization under non-equilibrium population dynamics.
Nurmi, Tuomas; Parvinen, Kalle
2013-03-21
We analyze the evolution of specialization in resource utilization in a mechanistically underpinned discrete-time model using the adaptive dynamics approach. We assume two nutritionally equivalent resources that in the absence of consumers grow sigmoidally towards a resource-specific carrying capacity. The consumers use resources according to the law of mass-action with rates involving trade-off. The resulting discrete-time model for the consumer population has over-compensatory dynamics. We illuminate the way non-equilibrium population dynamics affect the evolutionary dynamics of the resource consumption rates, and show that evolution to the trimorphic coexistence of a generalist and two specialists is possible due to asynchronous non-equilibrium population dynamics of the specialists. In addition, various forms of cyclic evolutionary dynamics are possible. Furthermore, evolutionary suicide may occur even without Allee effects and demographic stochasticity.
Non-equilibrium Flows of Reacting Air Components in Nozzles
NASA Astrophysics Data System (ADS)
Bazilevich, S. S.; Sinitsyn, K. A.; Nagnibeda, E. A.
2008-12-01
The paper presents the results of the investigation of non-equilibrium flows of reacting air mixtures in nozzles. State-to-state approach based on the solution of the equations for vibrational level populations of molecules and atomic concentrations coupled to the gas dynamics equations is used. For the 5-component air mixture (N2, O2, NO, N, O) non-equilibrium distributions and gasdynamical parameters are calculated for different conditions in a nozzle throat. The influence of various kinetic processes on distributions and gas dynamics parameters is studied. The paper presents the comparison of the results with ones obtained for binary mixtures of molecules and atoms and various models of elementary processes.
Entropy Production and Non-Equilibrium Steady States
NASA Astrophysics Data System (ADS)
Suzuki, Masuo
2013-01-01
The long-term issue of entropy production in transport phenomena is solved by separating the symmetry of the non-equilibrium density matrix ρ(t) in the von Neumann equation, as ρ(t) = ρs(t) + ρa(t) with the symmetric part ρs(t) and antisymmetric part ρa(t). The irreversible entropy production (dS/dt)irr is given in M. Suzuki, Physica A 390(2011)1904 by (dS/dt)irr = Tr( {H}(dρ s{(t)/dt))}/T for the Hamiltonian {H} of the relevant system. The general formulation of the extended von Neumann equation with energy supply and heat extraction is reviewed from the author's paper (M. S.,Physica A391(2012)1074). irreversibility; entropy production; transport phenomena; electric conduction; thermal conduction; linear response; Kubo formula; steady state; non-equilibrium density matrix; energy supply; symmetry-separated von Neumann equation; unboundedness.
Non-equilibrium Hybridization Expansion Impurity-solver
NASA Astrophysics Data System (ADS)
Dong, Qiaoyuan
2015-03-01
The study of non-equilibrium phenomena in strongly correlated systems has developed into one of the most active and exciting branches of condensed matter physics. Meanwhile, quantum impurity models play a prominent role as mathematical representations of quantum dots, single-molecule devices, and effective models for the dynamical mean field theory. We show results for a generalization of the hybridization expansion diagrammatic Monte Carlo technique for the Anderson impurity model. And we perform non-equilibrium calculations on the full Keldysh contour, where a dynamical sign problem vastly increases the complexity of real-time simulation. By further combining this method with a non-crossing approximation, our ``bold-line'' Monte Carlo can reach substantially longer times out of equilibrium than previously accessible, and provides an accurate description of quench and driven dynamics of correlated systems. Sponsored by the Department of Energy.
Towards Non-Equilibrium Dynamics with Trapped Ions
NASA Astrophysics Data System (ADS)
Silbert, Ariel; Jubin, Sierra; Doret, Charlie
2016-05-01
Atomic systems are superbly suited to the study of non-equilibrium dynamics. These systems' exquisite isolation from environmental perturbations leads to long relaxation times that enable exploration of far-from-equilibrium phenomena. One example of particular relevance to experiments in trapped ion quantum information processing, metrology, and precision spectroscopy is the approach to thermal equilibrium of sympathetically cooled linear ion chains. Suitable manipulation of experimental parameters permits exploration of the quantum-to-classical crossover between ballistic transport and diffusive, Fourier's Law conduction, a topic of interest not only to the trapped ion community but also for the development of microelectronic devices and other nanoscale structures. We present progress towards trapping chains of multiple co-trapped calcium isotopes geared towards measuring thermal equilibration and discuss plans for future experiments in non-equilibrium statistical mechanics. This work is supported by Cottrell College Science Award from the Research Corporation for Science Advancement and by Williams College.
Approach to non-equilibrium behaviour in quantum field theory
Kripfganz, J.; Perlt, H.
1989-05-01
We study the real-time evolution of quantum field theoretic systems in non-equilibrium situations. Results are presented for the example of scalar /lambda//phi//sup 4/ theory. The degrees of freedom are discretized by studying the system on a torus. Short-wavelength modes are integrated out to one-loop order. The long-wavelength modes considered to be the relevant degrees of freedom are treated by semiclassical phase-space methods. /copyright/ 1989 Academic Press, Inc.
Tunneling Measurements of Charge Imbalance of Non-Equilibrium Superconductors
NASA Astrophysics Data System (ADS)
Yagi, R.; Utsunomiya, K.; Tsuboi, K.; Kubota, T.; Terao, Y.; Ikebuchi, Y.
2008-10-01
We have observed excess current due to charge imbalance in the voltage-current characteristics of a superconductor-insulator-normal (SIN) tunnel junction connected to a non-equilibrium superconductor. It was found that that the excess current was unchanged against the bias voltage as expected from the theory of charge imbalance. The estimated excess current approximately agreed with the estimation from one-dimensional diffusion model of charge imbalance transport.
Novel mapping in non-equilibrium stochastic processes
NASA Astrophysics Data System (ADS)
Heseltine, James; Kim, Eun-jin
2016-04-01
We investigate the time-evolution of a non-equilibrium system in view of the change in information and provide a novel mapping relation which quantifies the change in information far from equilibrium and the proximity of a non-equilibrium state to the attractor. Specifically, we utilize a nonlinear stochastic model where the stochastic noise plays the role of incoherent regulation of the dynamical variable x and analytically compute the rate of change in information (information velocity) from the time-dependent probability distribution function. From this, we quantify the total change in information in terms of information length { L } and the associated action { J }, where { L } represents the distance that the system travels in the fluctuation-based, statistical metric space parameterized by time. As the initial probability density function’s mean position (μ) is decreased from the final equilibrium value {μ }* (the carrying capacity), { L } and { J } increase monotonically with interesting power-law mapping relations. In comparison, as μ is increased from {μ }*,{ L } and { J } increase slowly until they level off to a constant value. This manifests the proximity of the state to the attractor caused by a strong correlation for large μ through large fluctuations. Our proposed mapping relation provides a new way of understanding the progression of the complexity in non-equilibrium system in view of information change and the structure of underlying attractor.
Non-equilibrium fission processes in intermediate energy nuclear collisions
Loveland, W.; Casey, C.; Xu, Z.; Seaborg, G.T.; Aleklett, K.; Sihver, L.
1989-04-01
We have measured the target fragment yields, angular and energy distributions for the interaction of 12-16 MeV/A/sup 32/S with /sup 165/Ho and /sup 197/Au and for the interaction of 32 and 44 MeV/A /sup 40/Ar with /sup 197/Au. The Au fission fragments associated with the peripheral collision peak in the folding angle distribution originate in a normal, ''slow'' fission process in which statistical equilibrium has been established. At the two lowest projectile energies, the Au fission fragments associated with the central collision peak in the folding angle distribution originate in part from ''fast'' (/tau//approximately//sup /minus/23/s), non-equilibrium processes. Most of the Ho fission fragments originate in non- equilibrium processes. The fast, non-equilibrium process giving rise to these fragments has many of the characteristics of ''fast fission'', but the cross sections associated with these fragments are larger than one would expect from current theories of ''fast fission. '' 14 refs., 8 figs.
Characterization of non equilibrium effects on high quality critical flows
Camelo, E.; Lemonnier, H.; Ochterbeck, J.
1995-09-01
The appropriate design of various pieces of safety equipment such as relief systems, relies on the accurate description of critical flow phenomena. Most of the systems of industrial interest are willing to be described by one-dimensional area-averaged models and a large fraction of them involves multi-component high gas quality flows. Within these circumstances, the flow is very likely to be of an annular dispersed nature and its description by two-fluid models requires various closure relations. Among the most sensitive closures, there is the interfacial area and the liquid entrained fraction. The critical flowrate depends tremendously on the accurate description of the non equilibrium which results from the correctness of the closure equations. In this study, two-component flows are emphasized and non equilibrium results mainly form the differences in the phase velocities. It is therefore of the utmost importance to have reliable data to characterize non equilibrium phenomena and to assess the validity of the closure models. A comprehensive description of air-water nozzle flows, with emphasis on the effect of the nozzle geometry, has been undertaken and some of the results are presented here which helps understanding the overall flow dynamics. Besides the critical flowrate, the presented material includes pressure profiles, droplet size and velocity, liquid film flowrate and liquid film thickness.
Synchrotron radiation as an infrared source.
Stevenson, J R; Ellis, H; Bartlett, R
1973-12-01
The increasing availability of synchrotron radiation sources in a number of geographical regions of the world has motivated an evaluation of the radiation from electron accelerators and storage rings as a possible source for ir spectroscopy. As synchrotron radiation can be analytically described, a direct comparison is made with blackbody radiation for typical solid state spectroscopy. Both existing and proposed synchrotron radiation sources are found to be attractive in the ir. The ultrahigh vacuum environment of the source is compatible with clean surface investigations, the analytical description of the radiation is appropriate for calibration studies, and the continuous nature is suitable for Fourier spectroscopy or whenever a white light source is desirable.
Electron Broadening of Isolated Lines with Stationary Non-Equilibrium Level Populations
Iglesias, C A
2005-01-12
It is shown that a quantum kinetic theory approach to line broadening, extended to stationary non-equilibrium states, yields corrections to the standard electron impact widths of isolated lines that depend on the population of the radiator internal levels. A consistent classical limit from a general quantum treatment of the perturbing electrons also introduces corrections to the isolated line widths. Both effects are essential in preserving detailed-balance relations. Preliminary analysis indicates that these corrections may resolve existing discrepancies between theoretical and experimental widths of isolated lines. An experimental test of the results is proposed.
Fundamental Properties of Non-equilibrium Laser-Supported Detonation Wave
Shiraishi, Hiroyuki
2004-03-30
For developing laser propulsion, it is very important to analyze the mechanism of Laser-Supported Detonation (LSD), because it can generate high pressure and high temperature to be used by laser propulsion can be categorized as one type of hypersonic reacting flows, where exothermicity is supplied not by chemical reaction but by radiation absorption. I have numerically simulated the 1-D and Quasi-1-D LSD waves propagating through an inert gas, which absorbs CO2 gasdynamic laser, using a 2-temperature model. Calculated results show the fundamental properties of the non-equilibrium LSD Waves.
Radiation studies in the antiproton source
Church, M.
1990-09-10
Experiment E760 has a lead glass (Pb-G) calorimeter situated in the antiproton source tunnel in the accumulator ring at location A50. This location is exposed to radiation from several sources during antiproton stacking operations. A series of radiation studies has been performed over the last two years to determine the sources of this radiation and as a result, some shielding has been installed in the antiproton source in order to protect the lead glass from radiation damage.
The non-equilibrium nature of culinary evolution
NASA Astrophysics Data System (ADS)
Kinouchi, Osame; Diez-Garcia, Rosa W.; Holanda, Adriano J.; Zambianchi, Pedro; Roque, Antonio C.
2008-07-01
Food is an essential part of civilization, with a scope that ranges from the biological to the economic and cultural levels. Here, we study the statistics of ingredients and recipes taken from Brazilian, British, French and Medieval cookery books. We find universal distributions with scale invariant behaviour. We propose a copy-mutate process to model culinary evolution that fits our empirical data very well. We find a cultural 'founder effect' produced by the non-equilibrium dynamics of the model. Both the invariant and idiosyncratic aspects of culture are accounted for by our model, which may have applications in other kinds of evolutionary processes.
Shape characteristics of equilibrium and non-equilibrium fractal clusters.
Mansfield, Marc L; Douglas, Jack F
2013-07-28
It is often difficult in practice to discriminate between equilibrium and non-equilibrium nanoparticle or colloidal-particle clusters that form through aggregation in gas or solution phases. Scattering studies often permit the determination of an apparent fractal dimension, but both equilibrium and non-equilibrium clusters in three dimensions frequently have fractal dimensions near 2, so that it is often not possible to discriminate on the basis of this geometrical property. A survey of the anisotropy of a wide variety of polymeric structures (linear and ring random and self-avoiding random walks, percolation clusters, lattice animals, diffusion-limited aggregates, and Eden clusters) based on the principal components of both the radius of gyration and electric polarizability tensor indicates, perhaps counter-intuitively, that self-similar equilibrium clusters tend to be intrinsically anisotropic at all sizes, while non-equilibrium processes such as diffusion-limited aggregation or Eden growth tend to be isotropic in the large-mass limit, providing a potential means of discriminating these clusters experimentally if anisotropy could be determined along with the fractal dimension. Equilibrium polymer structures, such as flexible polymer chains, are normally self-similar due to the existence of only a single relevant length scale, and are thus anisotropic at all length scales, while non-equilibrium polymer structures that grow irreversibly in time eventually become isotropic if there is no difference in the average growth rates in different directions. There is apparently no proof of these general trends and little theoretical insight into what controls the universal anisotropy in equilibrium polymer structures of various kinds. This is an obvious topic of theoretical investigation, as well as a matter of practical interest. To address this general problem, we consider two experimentally accessible ratios, one between the hydrodynamic and gyration radii, the other
Comment on the Article ``Relativistic Non-Equilibrium Thermodynamics Revisited''
NASA Astrophysics Data System (ADS)
Muschik, Wolfgang; von Borzeszkowski, Horst-Heino
2007-05-01
There are two problematic items in García-Colín and Sandoval-Villalbazo's approach to “relativistic non-equilibrium thermodynamics” (L.S. García- Colín and A. Sandoval-Villalbazo, J. Non-Equilib. Thermodyn. 31, 2006, pp. 11-22). The paper does not follow the fundamentals of relativity theory; according to them, the energy-momentum tensor (EMT) has to include all energies of the considered system. Secondly, strange thermodynamic consequences result by using the presuppositions made by the authors. The paper is critically discussed and some shortcomings are elucidated.
Energy flow in non-equilibrium conformal field theory
NASA Astrophysics Data System (ADS)
Bernard, Denis; Doyon, Benjamin
2012-09-01
We study the energy current and its fluctuations in quantum gapless 1d systems far from equilibrium modeled by conformal field theory, where two separated halves are prepared at distinct temperatures and glued together at a point contact. We prove that these systems converge towards steady states, and give a general description of such non-equilibrium steady states in terms of quantum field theory data. We compute the large deviation function, also called the full counting statistics, of energy transfer through the contact. These are universal and satisfy fluctuation relations. We provide a simple representation of these quantum fluctuations in terms of classical Poisson processes whose intensities are proportional to Boltzmann weights.
Shape characteristics of equilibrium and non-equilibrium fractal clusters.
Mansfield, Marc L; Douglas, Jack F
2013-07-28
It is often difficult in practice to discriminate between equilibrium and non-equilibrium nanoparticle or colloidal-particle clusters that form through aggregation in gas or solution phases. Scattering studies often permit the determination of an apparent fractal dimension, but both equilibrium and non-equilibrium clusters in three dimensions frequently have fractal dimensions near 2, so that it is often not possible to discriminate on the basis of this geometrical property. A survey of the anisotropy of a wide variety of polymeric structures (linear and ring random and self-avoiding random walks, percolation clusters, lattice animals, diffusion-limited aggregates, and Eden clusters) based on the principal components of both the radius of gyration and electric polarizability tensor indicates, perhaps counter-intuitively, that self-similar equilibrium clusters tend to be intrinsically anisotropic at all sizes, while non-equilibrium processes such as diffusion-limited aggregation or Eden growth tend to be isotropic in the large-mass limit, providing a potential means of discriminating these clusters experimentally if anisotropy could be determined along with the fractal dimension. Equilibrium polymer structures, such as flexible polymer chains, are normally self-similar due to the existence of only a single relevant length scale, and are thus anisotropic at all length scales, while non-equilibrium polymer structures that grow irreversibly in time eventually become isotropic if there is no difference in the average growth rates in different directions. There is apparently no proof of these general trends and little theoretical insight into what controls the universal anisotropy in equilibrium polymer structures of various kinds. This is an obvious topic of theoretical investigation, as well as a matter of practical interest. To address this general problem, we consider two experimentally accessible ratios, one between the hydrodynamic and gyration radii, the other
Non Equilibrium Quantum Transport in a model of molecular conductor
NASA Astrophysics Data System (ADS)
Schiro', Marco; Fabrizio, Michele
2010-03-01
We investigate non equilibrium effects in quantum transport through a simple model of molecular conductor where a single electronic level coupled to a vibrational mode is hybridized with biased metallic contacts. Using a recently developed numerical method [1] we compute the time dependent current and extract steady state properties such as I-V characteristic, differential conductance and phonon distribution function. We also discuss transient effects and comment on the onset of bistability in the strong coupling regime. [4pt] [1] M. Schiro', M. Fabrizio, Phys.Rev.B 79 153302 (2009)
Optical Properties in Non-equilibrium Phase Transitions
Ao, T; Ping, Y; Widmann, K; Price, D F; Lee, E; Tam, H; Springer, P T; Ng, A
2006-01-05
An open question about the dynamical behavior of materials is how phase transition occurs in highly non-equilibrium systems. One important class of study is the excitation of a solid by an ultrafast, intense laser. The preferential heating of electrons by the laser field gives rise to initial states dominated by hot electrons in a cold lattice. Using a femtosecond laser pump-probe approach, we have followed the temporal evolution of the optical properties of such a system. The results show interesting correlation to non-thermal melting and lattice disordering processes. They also reveal a liquid-plasma transition when the lattice energy density reaches a critical value.
Shape characteristics of equilibrium and non-equilibrium fractal clusters
NASA Astrophysics Data System (ADS)
Mansfield, Marc L.; Douglas, Jack F.
2013-07-01
It is often difficult in practice to discriminate between equilibrium and non-equilibrium nanoparticle or colloidal-particle clusters that form through aggregation in gas or solution phases. Scattering studies often permit the determination of an apparent fractal dimension, but both equilibrium and non-equilibrium clusters in three dimensions frequently have fractal dimensions near 2, so that it is often not possible to discriminate on the basis of this geometrical property. A survey of the anisotropy of a wide variety of polymeric structures (linear and ring random and self-avoiding random walks, percolation clusters, lattice animals, diffusion-limited aggregates, and Eden clusters) based on the principal components of both the radius of gyration and electric polarizability tensor indicates, perhaps counter-intuitively, that self-similar equilibrium clusters tend to be intrinsically anisotropic at all sizes, while non-equilibrium processes such as diffusion-limited aggregation or Eden growth tend to be isotropic in the large-mass limit, providing a potential means of discriminating these clusters experimentally if anisotropy could be determined along with the fractal dimension. Equilibrium polymer structures, such as flexible polymer chains, are normally self-similar due to the existence of only a single relevant length scale, and are thus anisotropic at all length scales, while non-equilibrium polymer structures that grow irreversibly in time eventually become isotropic if there is no difference in the average growth rates in different directions. There is apparently no proof of these general trends and little theoretical insight into what controls the universal anisotropy in equilibrium polymer structures of various kinds. This is an obvious topic of theoretical investigation, as well as a matter of practical interest. To address this general problem, we consider two experimentally accessible ratios, one between the hydrodynamic and gyration radii, the other
Non-equilibrium hot carrier dynamics in plasmonic nanostructures
NASA Astrophysics Data System (ADS)
Narang, Prineha; Sundararaman, Ravishankar; Jermyn, Adam; Cortes, Emiliano; Maier, Stefan A.; Goddard, William A., III
Decay of surface plasmons to hot carriers is a new direction that has attracted considerable fundamental and application interest, yet a fundamental understanding of ultrafast plasmon decay processes and the underlying microscopic mechanisms remain incomplete. Ultrafast experiments provide insights into the relaxation of non-equilibrium carriers at the tens and hundreds of femtoseconds time scales, but do not yet directly probe shorter times with nanometer spatial resolution. Here we report the first ab initio calculations of non equilibrium transport of plasmonic hot carriers in metals and experimental observation of the injection of these carriers into molecules tethered to the metal surface. Specifically, metallic nanoantennas functionalized with a molecular monolayer allow for the direct probing of electron injection via surface enhanced Raman spectroscopy of the original and reduced molecular species. We combine first principles calculations of electron-electron and electron-phonon scattering rates with Boltzmann transport simulations to predict the ultrafast dynamics and transport of carriers in real materials. We also predict and compare the evolution of electron distributions in ultrafast experiments on noble metal nanoparticles.
Light-induced electronic non-equilibrium in plasmonic particles.
Kornbluth, Mordechai; Nitzan, Abraham; Seideman, Tamar
2013-05-01
We consider the transient non-equilibrium electronic distribution that is created in a metal nanoparticle upon plasmon excitation. Following light absorption, the created plasmons decohere within a few femtoseconds, producing uncorrelated electron-hole pairs. The corresponding non-thermal electronic distribution evolves in response to the photo-exciting pulse and to subsequent relaxation processes. First, on the femtosecond timescale, the electronic subsystem relaxes to a Fermi-Dirac distribution characterized by an electronic temperature. Next, within picoseconds, thermalization with the underlying lattice phonons leads to a hot particle in internal equilibrium that subsequently equilibrates with the environment. Here we focus on the early stage of this multistep relaxation process, and on the properties of the ensuing non-equilibrium electronic distribution. We consider the form of this distribution as derived from the balance between the optical absorption and the subsequent relaxation processes, and discuss its implication for (a) heating of illuminated plasmonic particles, (b) the possibility to optically induce current in junctions, and (c) the prospect for experimental observation of such light-driven transport phenomena. PMID:23656152
Non-equilibrium Thermodynamics of Rayleigh-Taylor Instability
NASA Astrophysics Data System (ADS)
Sengupta, Tapan K.; Sengupta, Aditi; Sengupta, Soumyo; Bhole, Ashish; Shruti, K. S.
2016-04-01
Here, the fundamental problem of Rayleigh-Taylor instability (RTI) is studied by direct numerical simulation (DNS), where the two air masses at different temperatures, kept apart initially by a non-conducting horizontal interface in a 2D box, are allowed to mix. Upon removal of the partition, mixing is controlled by RTI, apart from mutual mass, momentum, and energy transfer. To accentuate the instability, the top chamber is filled with the heavier (lower temperature) air, which rests atop the chamber containing lighter air. The partition is positioned initially at mid-height of the box. As the fluid dynamical system considered is completely isolated from outside, the DNS results obtained without using Boussinesq approximation will enable one to study non-equilibrium thermodynamics of a finite reservoir undergoing strong irreversible processes. The barrier is removed impulsively, triggering baroclinic instability by non-alignment of density, and pressure gradient by ambient disturbances via the sharp discontinuity at the interface. Adopted DNS method has dispersion relation preservation properties with neutral stability and does not require any external initial perturbations. The complete inhomogeneous problem with non-periodic, no-slip boundary conditions is studied by solving compressible Navier-Stokes equation, without the Boussinesq approximation. This is important as the temperature difference between the two air masses considered is high enough (Δ T = 70 K) to invalidate Boussinesq approximation. We discuss non-equilibrium thermodynamical aspects of RTI with the help of numerical results for density, vorticity, entropy, energy, and enstrophy.
Non-equilibrium theory of arrested spinodal decomposition
Olais-Govea, José Manuel; López-Flores, Leticia; Medina-Noyola, Magdaleno
2015-11-07
The non-equilibrium self-consistent generalized Langevin equation theory of irreversible relaxation [P. E. Ramŕez-González and M. Medina-Noyola, Phys. Rev. E 82, 061503 (2010); 82, 061504 (2010)] is applied to the description of the non-equilibrium processes involved in the spinodal decomposition of suddenly and deeply quenched simple liquids. For model liquids with hard-sphere plus attractive (Yukawa or square well) pair potential, the theory predicts that the spinodal curve, besides being the threshold of the thermodynamic stability of homogeneous states, is also the borderline between the regions of ergodic and non-ergodic homogeneous states. It also predicts that the high-density liquid-glass transition line, whose high-temperature limit corresponds to the well-known hard-sphere glass transition, at lower temperature intersects the spinodal curve and continues inside the spinodal region as a glass-glass transition line. Within the region bounded from below by this low-temperature glass-glass transition and from above by the spinodal dynamic arrest line, we can recognize two distinct domains with qualitatively different temperature dependence of various physical properties. We interpret these two domains as corresponding to full gas-liquid phase separation conditions and to the formation of physical gels by arrested spinodal decomposition. The resulting theoretical scenario is consistent with the corresponding experimental observations in a specific colloidal model system.
Non-equilibrium magnetic interactions in strongly correlated systems
Secchi, A.; Brener, S.; Lichtenstein, A.I.; Katsnelson, M.I.
2013-06-15
We formulate a low-energy theory for the magnetic interactions between electrons in the multi-band Hubbard model under non-equilibrium conditions determined by an external time-dependent electric field which simulates laser-induced spin dynamics. We derive expressions for dynamical exchange parameters in terms of non-equilibrium electronic Green functions and self-energies, which can be computed, e.g., with the methods of time-dependent dynamical mean-field theory. Moreover, we find that a correct description of the system requires, in addition to exchange, a new kind of magnetic interaction, that we name twist exchange, which formally resembles Dzyaloshinskii–Moriya coupling, but is not due to spin–orbit, and is actually due to an effective three-spin interaction. Our theory allows the evaluation of the related time-dependent parameters as well. -- Highlights: •We develop a theory for magnetism of strongly correlated systems out of equilibrium. •Our theory is suitable for laser-induced ultrafast magnetization dynamics. •We write time-dependent exchange parameters in terms of electronic Green functions. •We find a new magnetic interaction, a “twist exchange”. •We give general expressions for magnetic noise in itinerant-electron systems.
Non-equilibrium theory of arrested spinodal decomposition.
Olais-Govea, José Manuel; López-Flores, Leticia; Medina-Noyola, Magdaleno
2015-11-01
The non-equilibrium self-consistent generalized Langevin equation theory of irreversible relaxation [P. E. Ramŕez-González and M. Medina-Noyola, Phys. Rev. E 82, 061503 (2010); 82, 061504 (2010)] is applied to the description of the non-equilibrium processes involved in the spinodal decomposition of suddenly and deeply quenched simple liquids. For model liquids with hard-sphere plus attractive (Yukawa or square well) pair potential, the theory predicts that the spinodal curve, besides being the threshold of the thermodynamic stability of homogeneous states, is also the borderline between the regions of ergodic and non-ergodic homogeneous states. It also predicts that the high-density liquid-glass transition line, whose high-temperature limit corresponds to the well-known hard-sphere glass transition, at lower temperature intersects the spinodal curve and continues inside the spinodal region as a glass-glass transition line. Within the region bounded from below by this low-temperature glass-glass transition and from above by the spinodal dynamic arrest line, we can recognize two distinct domains with qualitatively different temperature dependence of various physical properties. We interpret these two domains as corresponding to full gas-liquid phase separation conditions and to the formation of physical gels by arrested spinodal decomposition. The resulting theoretical scenario is consistent with the corresponding experimental observations in a specific colloidal model system. PMID:26547174
Non-Equilibrium Critical Behavior: An Extended Irreversible Thermodynamics Approach
NASA Astrophysics Data System (ADS)
Hernández-Lemus, Enrique; García-Colín, Leopoldo S.
2006-11-01
Critical phenomena in non-equilibrium systems have been studied by means of a wide variety of theoretical and experimental approaches. Mode-coupling, renormalization group, complex Lie algebras and diagrammatic techniques are some of the usual theoretical tools. Experimental studies include light and inelastic neutron scattering, X-ray photon correlation spectroscopy, microwave interferometry and several other techniques. Nevertheless, no conclusive treatment has been developed from the basic principles of a thermodynamic theory of irreversible processes. We have developed a formalism in which we obtain correlation functions as
The non-equilibrium and energetic cost of sensory adaptation
Lan, G.; Sartori, Pablo; Tu, Y.
2011-03-24
Biological sensory systems respond to external signals in short time and adapt to permanent environmental changes over a longer timescale to maintain high sensitivity in widely varying environments. In this work we have shown how all adaptation dynamics are intrinsically non-equilibrium and free energy is dissipated. We show that the dissipated energy is utilized to maintain adaptation accuracy. A universal relation between the energy dissipation and the optimum adaptation accuracy is established by both a general continuum model and a discrete model i n the specific case of the well-known E. coli chemo-sensory adaptation. Our study suggests that cellular level adaptations are fueled by hydrolysis of high energy biomolecules, such as ATP. The relevance of this work lies on linking the functionality of a biological system (sensory adaptation) with a concept rooted in statistical physics (energy dissipation), by a mathematical law. This has been made possible by identifying a general sensory system with a non-equilibrium steady state (a stationary state in which the probability current is not zero, but its divergence is, see figure), and then numerically and analytically solving the Fokker-Planck and Master Equations which describe the sensory adaptive system. The application of our general results to the case of E. Coli has shed light on why this system uses the high energy SAM molecule to perform adaptation, since using the more common ATP would not suffice to obtain the required adaptation accuracy.
The non-equilibrium and energetic cost of sensory adaptation
NASA Astrophysics Data System (ADS)
Lan, G.; Sartori, Pablo; Tu, Y.
2011-03-01
Biological sensory systems respond to external signals in short time and adapt to permanent environmental changes over a longer timescale to maintain high sensitivity in widely varying environments. In this work we have shown how all adaptation dynamics are intrinsically non-equilibrium and free energy is dissipated. We show that the dissipated energy is utilized to maintain adaptation accuracy. A universal relation between the energy dissipation and the optimum adaptation accuracy is established by both a general continuum model and a discrete model i n the specific case of the well-known E. coli chemo-sensory adaptation. Our study suggests that cellular level adaptations are fueled by hydrolysis of high energy biomolecules, such as ATP. The relevance of this work lies on linking the functionality of a biological system (sensory adaptation) with a concept rooted in statistical physics (energy dissipation), by a mathematical law. This has been made possible by identifying a general sensory system with a non-equilibrium steady state (a stationary state in which the probability current is not zero, but its divergence is, see figure), and then numerically and analytically solving the Fokker-Planck and Master Equations which describe the sensory adaptive system. The application of our general results to the case of E. Coli has shed light on why this system uses the high energy SAM molecule to perform adaptation, since using the more common ATP would not suffice to obtain the required adaptation accuracy.
Non-equilibrium thermodynamics analysis of transcriptional regulation kinetics
NASA Astrophysics Data System (ADS)
Hernández-Lemus, Enrique; Tovar, Hugo; Mejía, Carmen
2014-12-01
Gene expression in eukaryotic cells is an extremely complex and interesting phenomenon whose dynamics are controlled by a large number of subtle physicochemical processes commonly described by means of gene regulatory networks. Such networks consist in a series of coupled chemical reactions, conformational changes, and other biomolecular processes involving the interaction of the DNA molecule itself with a number of proteins usually called transcription factors as well as enzymes and other components. The kinetics behind the functioning of such gene regulatory networks are largely unknown, though its description in terms of non-equilibrium thermodynamics has been discussed recently. In this work we will derive general kinetic equations for a gene regulatory network from a non-equilibrium thermodynamical description and discuss its use in understanding the free energy constrains imposed in the network structure. We also will discuss explicit expressions for the kinetics of a simple model of gene regulation and show that the kinetic role of mRNA decay during the RNA synthesis stage (or transcription) is somehow limited due to the comparatively low values of decay rates. At the level discussed here, this implies a decoupling of the kinetics of mRNA synthesis and degradation a fact that may become quite useful when modeling gene regulatory networks from experimental data on whole genome gene expression.
C-Field Methods for Non-Equilibrium Bose Gases
NASA Astrophysics Data System (ADS)
Davis, Matthew J.; Wright, Tod M.; Blakie, P. Blair; Bradley, Ashton S.; Ballagh, Rob J.; Gardiner, Crispin W.
2013-02-01
We review c-field methods for simulating the non-equilibrium dynamics of degenerate Bose gases beyond the mean-field Gross-Pitaevskii approximation. We describe three separate approaches that utilise similar numerical methods, but have distinct regimes of validity. Systems at finite temperature can be treated with either the closed-system projected Gross-Pitaevskii equation (PGPE), or the open-system stochastic projected Gross-Pitaevskii equation (SPGPE). These are both applicable in quantum degenerate regimes in which thermal fluctuations are significant. At low or zero temperature, the truncated Wigner projected Gross Pitaevskii equation (TWPGPE) allows for the simulation of systems in which spontaneous collision processes seeded by quantum fluctuations are important. We describe the regimes of validity of each of these methods, and discuss their relationships to one another, and to other simulation techniques for the dynamics of Bose gases. The utility of the SPGPE formalism in modelling non-equilibrium Bose gases is illustrated by its application to the dynamics of spontaneous vortex formation in the growth of a Bose-Einstein condensate.
A Black-box Modelling Engine for Discharge Produced Plasma Radiation Sources
NASA Astrophysics Data System (ADS)
Zakharov, S. V.; Choi, P.; Krukovskiy, A. Y.; Novikov, V. G.; Zakharov, V. S.; Zhang, Q.
2006-01-01
A Blackbox Modelling Engine (BME), is an instrument based on the adaptation of the RMHD code Z*, integrated into a specific computation environment to provide a turn key simulation instrument and to enable routine plasma modelling without specialist knowledge in numerical computation. Two different operating modes are provided: Detailed Physics mode & Fast Numerics mode. In the Detailed Physics mode, non-stationary, non-equilibrium radiation physics have been introduced to allow the modelling of transient plasmas in experimental geometry. In the Fast Numerics mode, the system architecture and the radiation transport is simplified to significantly accelerate the computation rate. The Fast Numerics mode allows the BME to be used realistically in parametric scanning to explore complex physical set up, before using the Detailed Physics mode. As an example of the results from the BME modelling, the EUV source plasma dynamics in the pulsed capillary discharge are presented.
Non-equilibrium phase transitions in a liquid crystal
NASA Astrophysics Data System (ADS)
Dan, K.; Roy, M.; Datta, A.
2015-09-01
The present manuscript describes kinetic behaviour of the glass transition and non-equilibrium features of the "Nematic-Isotropic" (N-I) phase transition of a well known liquid crystalline material N-(4-methoxybenzylidene)-4-butylaniline from the effects of heating rate and initial temperature on the transitions, through differential scanning calorimetry (DSC), Fourier transform infrared and fluorescence spectroscopy. Around the vicinity of the glass transition temperature (Tg), while only a change in the baseline of the ΔCp vs T curve is observed for heating rate (β) > 5 K min-1, consistent with a glass transition, a clear peak for β ≤ 5 K min-1 and the rapid reduction in the ΔCp value from the former to the latter rate correspond to an order-disorder transition and a transition from ergodic to non-ergodic behaviour. The ln β vs 1000/T curve for the glass transition shows convex Arrhenius behaviour that can be explained very well by a purely entropic activation barrier [Dan et al., Eur. Phys. Lett. 108, 36007 (2014)]. Fourier transform infrared spectroscopy indicates sudden freezing of the out-of-plane distortion vibrations of the benzene rings around the glass transition temperature and a considerable red shift indicating enhanced coplanarity of the benzene rings and, consequently, enhancement in the molecular ordering compared to room temperature. We further provide a direct experimental evidence of the non-equilibrium nature of the N-I transition through the dependence of this transition temperature (TNI) and associated enthalpy change (ΔH) on the initial temperature (at fixed β-values) for the DSC scans. A plausible qualitative explanation based on Mesquita's extension of Landau-deGennes theory [O. N. de Mesquita, Braz. J. Phys. 28, 257 (1998)] has been put forward. The change in the molecular ordering from nematic to isotropic phase has been investigated through fluorescence anisotropy measurements where the order parameter, quantified by the
Non-equilibrium phase transitions in a liquid crystal.
Dan, K; Roy, M; Datta, A
2015-09-01
The present manuscript describes kinetic behaviour of the glass transition and non-equilibrium features of the "Nematic-Isotropic" (N-I) phase transition of a well known liquid crystalline material N-(4-methoxybenzylidene)-4-butylaniline from the effects of heating rate and initial temperature on the transitions, through differential scanning calorimetry (DSC), Fourier transform infrared and fluorescence spectroscopy. Around the vicinity of the glass transition temperature (Tg), while only a change in the baseline of the ΔCp vs T curve is observed for heating rate (β) > 5 K min(-1), consistent with a glass transition, a clear peak for β ≤ 5 K min(-1) and the rapid reduction in the ΔCp value from the former to the latter rate correspond to an order-disorder transition and a transition from ergodic to non-ergodic behaviour. The ln β vs 1000/T curve for the glass transition shows convex Arrhenius behaviour that can be explained very well by a purely entropic activation barrier [Dan et al., Eur. Phys. Lett. 108, 36007 (2014)]. Fourier transform infrared spectroscopy indicates sudden freezing of the out-of-plane distortion vibrations of the benzene rings around the glass transition temperature and a considerable red shift indicating enhanced coplanarity of the benzene rings and, consequently, enhancement in the molecular ordering compared to room temperature. We further provide a direct experimental evidence of the non-equilibrium nature of the N-I transition through the dependence of this transition temperature (TNI) and associated enthalpy change (ΔH) on the initial temperature (at fixed β-values) for the DSC scans. A plausible qualitative explanation based on Mesquita's extension of Landau-deGennes theory [O. N. de Mesquita, Braz. J. Phys. 28, 257 (1998)] has been put forward. The change in the molecular ordering from nematic to isotropic phase has been investigated through fluorescence anisotropy measurements where the order parameter, quantified by the
General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures
Liu, Yen Vinokur, Marcel; Panesi, Marco; Sahai, Amal
2015-04-07
This paper opens a new door to macroscopic modeling for thermal and chemical non-equilibrium. In a game-changing approach, we discard conventional theories and practices stemming from the separation of internal energy modes and the Landau-Teller relaxation equation. Instead, we solve the fundamental microscopic equations in their moment forms but seek only optimum representations for the microscopic state distribution function that provides converged and time accurate solutions for certain macroscopic quantities at all times. The modeling makes no ad hoc assumptions or simplifications at the microscopic level and includes all possible collisional and radiative processes; it therefore retains all non-equilibrium fluid physics. We formulate the thermal and chemical non-equilibrium macroscopic equations and rate coefficients in a coupled and unified fashion for gases undergoing completely general transitions. All collisional partners can have internal structures and can change their internal energy states after transitions. The model is based on the reconstruction of the state distribution function. The internal energy space is subdivided into multiple groups in order to better describe non-equilibrium state distributions. The logarithm of the distribution function in each group is expressed as a power series in internal energy based on the maximum entropy principle. The method of weighted residuals is applied to the microscopic equations to obtain macroscopic moment equations and rate coefficients succinctly to any order. The model’s accuracy depends only on the assumed expression of the state distribution function and the number of groups used and can be self-checked for accuracy and convergence. We show that the macroscopic internal energy transfer, similar to mass and momentum transfers, occurs through nonlinear collisional processes and is not a simple relaxation process described by, e.g., the Landau-Teller equation. Unlike the classical vibrational energy
General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures.
Liu, Yen; Panesi, Marco; Sahai, Amal; Vinokur, Marcel
2015-04-01
This paper opens a new door to macroscopic modeling for thermal and chemical non-equilibrium. In a game-changing approach, we discard conventional theories and practices stemming from the separation of internal energy modes and the Landau-Teller relaxation equation. Instead, we solve the fundamental microscopic equations in their moment forms but seek only optimum representations for the microscopic state distribution function that provides converged and time accurate solutions for certain macroscopic quantities at all times. The modeling makes no ad hoc assumptions or simplifications at the microscopic level and includes all possible collisional and radiative processes; it therefore retains all non-equilibrium fluid physics. We formulate the thermal and chemical non-equilibrium macroscopic equations and rate coefficients in a coupled and unified fashion for gases undergoing completely general transitions. All collisional partners can have internal structures and can change their internal energy states after transitions. The model is based on the reconstruction of the state distribution function. The internal energy space is subdivided into multiple groups in order to better describe non-equilibrium state distributions. The logarithm of the distribution function in each group is expressed as a power series in internal energy based on the maximum entropy principle. The method of weighted residuals is applied to the microscopic equations to obtain macroscopic moment equations and rate coefficients succinctly to any order. The model's accuracy depends only on the assumed expression of the state distribution function and the number of groups used and can be self-checked for accuracy and convergence. We show that the macroscopic internal energy transfer, similar to mass and momentum transfers, occurs through nonlinear collisional processes and is not a simple relaxation process described by, e.g., the Landau-Teller equation. Unlike the classical vibrational energy
General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures.
Liu, Yen; Panesi, Marco; Sahai, Amal; Vinokur, Marcel
2015-04-01
This paper opens a new door to macroscopic modeling for thermal and chemical non-equilibrium. In a game-changing approach, we discard conventional theories and practices stemming from the separation of internal energy modes and the Landau-Teller relaxation equation. Instead, we solve the fundamental microscopic equations in their moment forms but seek only optimum representations for the microscopic state distribution function that provides converged and time accurate solutions for certain macroscopic quantities at all times. The modeling makes no ad hoc assumptions or simplifications at the microscopic level and includes all possible collisional and radiative processes; it therefore retains all non-equilibrium fluid physics. We formulate the thermal and chemical non-equilibrium macroscopic equations and rate coefficients in a coupled and unified fashion for gases undergoing completely general transitions. All collisional partners can have internal structures and can change their internal energy states after transitions. The model is based on the reconstruction of the state distribution function. The internal energy space is subdivided into multiple groups in order to better describe non-equilibrium state distributions. The logarithm of the distribution function in each group is expressed as a power series in internal energy based on the maximum entropy principle. The method of weighted residuals is applied to the microscopic equations to obtain macroscopic moment equations and rate coefficients succinctly to any order. The model's accuracy depends only on the assumed expression of the state distribution function and the number of groups used and can be self-checked for accuracy and convergence. We show that the macroscopic internal energy transfer, similar to mass and momentum transfers, occurs through nonlinear collisional processes and is not a simple relaxation process described by, e.g., the Landau-Teller equation. Unlike the classical vibrational energy
Non-equilibrium Air Plasma for Wound Bleeding Control
NASA Astrophysics Data System (ADS)
Kuo, Spencer P.; Chen, Cheng-Yen; Lin, Chuan-Shun; Chiang, Shu-Hsing
A low temperature non-equilibrium air plasma spray is tested as a blood coagulator. Emission spectroscopy of the plasma effluent indicates that it carries abundant reactive atomic oxygen (RAO), which can activate erythrocyte - platelet interactions to enhance blood coagulation for plug formation. Tests of the device for wound bleeding control were performed on pigs. Four types of wounds, straight cut and cross cut in the ham area, a hole in an ear saphenous vein, and a cut to an ear artery, were examined. The results showed that this plasma spray could effectively stop the bleeding and reduced the bleeding time considerably. Post-Operative observation of straight cut and cross cut wound healing was carried out. It was found that the plasma treatment had a positive impact on wound healing, in particular, of the cross cut wound; its healing time was shortened by a half.
Biological Implications of Dynamical Phases in Non-equilibrium Networks
NASA Astrophysics Data System (ADS)
Murugan, Arvind; Vaikuntanathan, Suriyanarayanan
2016-03-01
Biology achieves novel functions like error correction, ultra-sensitivity and accurate concentration measurement at the expense of free energy through Maxwell Demon-like mechanisms. The design principles and free energy trade-offs have been studied for a variety of such mechanisms. In this review, we emphasize a perspective based on dynamical phases that can explain commonalities shared by these mechanisms. Dynamical phases are defined by typical trajectories executed by non-equilibrium systems in the space of internal states. We find that coexistence of dynamical phases can have dramatic consequences for function vs free energy cost trade-offs. Dynamical phases can also provide an intuitive picture of the design principles behind such biological Maxwell Demons.
Non-Equilibrium Hyperbolic Transport in Transcriptional Regulation
Hernández-Lemus, Enrique; Correa-Rodríguez, María D.
2011-01-01
In this work we studied memory and irreversible transport phenomena in a non-equilibrium thermodynamical model for genomic transcriptional regulation. Transcriptional regulation possess an extremely complex phenomenology, and it is, of course, of foremost importance in organismal cell development and in the pathogenesis of complex diseases. A better understanding of the way in which these processes occur is mandatory to optimize the construction of gene regulatory networks, but also to connect these networks with multi-scale phenomena (e.g. metabolism, signalling pathways, etc.) under an integrative Systems Biology-like vision. In this paper we analyzed three simple mechanisms of genetic stimulation: an instant pulse, a periodic biochemical signal and a saturation process with sigmoidal kinetics and from these we derived the system's thermodynamical response, in the form of, for example, anomalous transcriptional bursts. PMID:21754990
Thermal Non-equilibrium Consistent with Widespread Cooling
NASA Technical Reports Server (NTRS)
Winebarger, A.; Lionello, R.; Mikic, Z.; Linker, J.; Mok, Y.
2014-01-01
Time correlation analysis has been used to show widespread cooling in the solar corona; this cooling has been interpreted as a result of impulsive (nanoflare) heating. In this work, we investigate wide-spread cooling using a 3D model for a solar active region which has been heated with highly stratified heating. This type of heating drives thermal non-equilibrium solutions, meaning that though the heating is effectively steady, the density and temperature in the solution are not. We simulate the expected observations in narrowband EUV images and apply the time correlation analysis. We find that the results of this analysis are qualitatively similar to the observed data. We discuss additional diagnostics that may be applied to differentiate between these two heating scenarios.
Non Equilibrium Fluctuations In The Degenerated Polarizable Plasma
Belyi, V. V.; Kukharenko, Yu. A.
2009-04-23
The quantum plasma of Bose and Fermi particles is considered. A scheme of equation linearization for density matrix with the exchange interaction taken in account is proposed and the equation solution is found. An expression for Hartree- Fock dielectric permittivity with the exchange interaction is obtained. This interaction is taken into account in the exchange scattering amplitude. With the use of obtained solutions the non-equilibrium spectral function of electric field fluctuations in presence of exchange interaction and medium polarization is found. It is shown that in the state of thermodynamic equilibrium a Fluctuation-Dissipation Theorem holds. An expression for the system's response to an external electric field in presence of exchange interaction is given.
Non-equilibrium plasma reactors for organic solvent destruction
Yang, C.L.; Beltran, M.R.; Kravets, Z.
1997-12-31
Two non-equilibrium plasma reactors were evaluated for their ability to destroy three widely used organic solvents, i.e., 2-butanone, toluene and ethyl acetate. The catalyzed plasma reactor (CPR) with 6 mm glass beads destroys 98% of 50 ppm toluene in air at 24 kV/cm and space velocities of 1,400 v/v/hr. Eighty-five percent of ethyl acetate and 2-butanone are destroyed under the same conditions. The tubular plasma reactor (TPR) has an efficiency of 10% to 20% lower than that of a CPR under the same conditions. The 1,400 v/v/hr in a CPR is equal to a residence time of 2.6 seconds in a TPR. The operating temperatures, corona characteristics, as well as the kinetics of VOC destruction in both TPR and CPR were studied.
Complementary relations in non-equilibrium stochastic processes
NASA Astrophysics Data System (ADS)
Kim, Eun-jin; Nicholson, S. B.
2015-08-01
We present novel complementary relations in non-equilibrium stochastic processes. Specifically, by utilising path integral formulation, we derive statistical measures (entropy, information, and work) and investigate their dependence on variables (x, v), reference frames, and time. In particular, we show that the equilibrium state maximises the simultaneous information quantified by the product of the Fisher information based on x and v while minimising the simultaneous disorder/uncertainty quantified by the sum of the entropy based on x and v as well as by the product of the variances of the PDFs of x and v. We also elucidate the difference between Eulerian and Lagrangian entropy. Our theory naturally leads to Hamilton-Jacobi relation for forced-dissipative systems.
Plasma diagnostics of non-equilibrium atmospheric plasma jets
NASA Astrophysics Data System (ADS)
Shashurin, Alexey; Scott, David; Keidar, Michael; Shneider, Mikhail
2014-10-01
Intensive development and biomedical application of non-equilibrium atmospheric plasma jet (NEAPJ) facilitates rapid growth of the plasma medicine field. The NEAPJ facility utilized at the George Washington University (GWU) demonstrated efficacy for treatment of various cancer types (lung, bladder, breast, head, neck, brain and skin). In this work we review recent advances of the research conducted at GWU concerned with the development of NEAPJ diagnostics including Rayleigh Microwave Scattering setup, method of streamer scattering on DC potential, Rogowski coils, ICCD camera and optical emission spectroscopy. These tools allow conducting temporally-resolved measurements of plasma density, electrical potential, charge and size of the streamer head, electrical currents flowing though the jet, ionization front propagation speed etc. Transient dynamics of plasma and discharge parameters will be considered and physical processes involved in the discharge will be analyzed including streamer breakdown, electrical coupling of the streamer tip with discharge electrodes, factors determining NEAPJ length, cross-sectional shape and propagation path etc.
Non-equilibrium Thermodynamics of the Longitudinal Spin Seebeck Effect
NASA Astrophysics Data System (ADS)
Basso, Vittorio; Ferraro, Elena; Sola, Alessandro; Magni, Alessandro; Kuepferling, Michaela; Pasquale, Massimo
In this paper we employ non equilibrium thermodynamics of fluxes and forces to describe magnetization and heat transport. By the theory we are able to identify the thermodynamic driving force of the magnetization current as the gradient of the effective field ▿H*. This definition permits to define the spin Seebeck coefficient ɛM which relates ▿H* and the temperature gradient ▿T. By applying the theory to the geometry of the longitudinal spin Seebeck effect we are able to obtain the optimal conditions for generating large magnetization currents. Furthermore, by using the results of recent experiments, we obtain an order of magnitude for the value of ɛM ∼ 10-2 TK-1 for yttrium iron garnet (Y3Fe5O12).
Closure conditions for non-equilibrium multi-component models
NASA Astrophysics Data System (ADS)
Müller, S.; Hantke, M.; Richter, P.
2016-07-01
A class of non-equilibrium models for compressible multi-component fluids in multi-dimensions is investigated taking into account viscosity and heat conduction. These models are subject to the choice of interfacial pressures and interfacial velocity as well as relaxation terms for velocity, pressure, temperature and chemical potentials. Sufficient conditions are derived for these quantities that ensure meaningful physical properties such as a non-negative entropy production, thermodynamical stability, Galilean invariance and mathematical properties such as hyperbolicity, subcharacteristic property and existence of an entropy-entropy flux pair. For the relaxation of chemical potentials, a two-component and a three-component models for vapor-water and gas-water-vapor, respectively, are considered.
NASA Astrophysics Data System (ADS)
Reynolds, J. F.
2001-12-01
The dynamics of rangeland ecosystems involve many factors whose simultaneous action and complex interactions are poorly understood at the relevant temporal and spatial scales. Nonlinear, complex interactions among the drivers of change are some of the main sources of this uncertainty. This includes regime shifts in climate, water movement across landscapes (e.g., key feedbacks between rainfall interception, soil erosion, and nutrient transport), exotic species invasions, and plant physiological responses to episodic rainfall events. In recognition of these nonlinearities, during the past several decades there has been a paradigm switch in ecology, from a `balance of nature' to equilibrium/stability to non-equilibrium. Arguably, in no other area of ecology has the equilibrium/non-equilibrium debate been as influential in shaping science discourse, research priorities, and management approaches as in arid and semiarid rangeland grazing systems. For over 50 years, the equilibrium or linear perspective has been the dominant model used for assessment and management in rangeland ecosystems, but it is now recognized that the equilibrium model per se does not, for example, account for the existence of multiple `climax' states that may arise out of unique plant-soil-atmosphere interactions, and that removing a disturbance (e.g., grazing) does not automatically result in a resumption of a orderly succession progression. To introduce this session, I will present examples of non-linear extremes and threshold controls on coupled water and nitrogen dynamics in arid/semiarid ecosystems and show how this work has contributed to the evolution of the non-equilibrium paradigm in rangeland ecology.
Modeling Inflation Using a Non-Equilibrium Equation of Exchange
NASA Technical Reports Server (NTRS)
Chamberlain, Robert G.
2013-01-01
Inflation is a change in the prices of goods that takes place without changes in the actual values of those goods. The Equation of Exchange, formulated clearly in a seminal paper by Irving Fisher in 1911, establishes an equilibrium relationship between the price index P (also known as "inflation"), the economy's aggregate output Q (also known as "the real gross domestic product"), the amount of money available for spending M (also known as "the money supply"), and the rate at which money is reused V (also known as "the velocity of circulation of money"). This paper offers first a qualitative discussion of what can cause these factors to change and how those causes might be controlled, then develops a quantitative model of inflation based on a non-equilibrium version of the Equation of Exchange. Causal relationships are different from equations in that the effects of changes in the causal variables take time to play out-often significant amounts of time. In the model described here, wages track prices, but only after a distributed lag. Prices change whenever the money supply, aggregate output, or the velocity of circulation of money change, but only after a distributed lag. Similarly, the money supply depends on the supplies of domestic and foreign money, which depend on the monetary base and a variety of foreign transactions, respectively. The spreading of delays mitigates the shocks of sudden changes to important inputs, but the most important aspect of this model is that delays, which often have dramatic consequences in dynamic systems, are explicitly incorporated.macroeconomics, inflation, equation of exchange, non-equilibrium, Athena Project
Non-Equilibrium Phenomena in High Power Beam Materials Processing
NASA Astrophysics Data System (ADS)
Tosto, Sebastiano
2004-03-01
The paper concerns some aspects of non-equilibrium materials processing with high power beams. Three examples show that the formation of metastable phases plays a crucial role to understand the effects of beam-matter interaction: (i) modeling of pulsed laser induced thermal sputtering; (ii) formation of metastable phases during solidification of the melt pool; (i) possibility of carrying out heat treatments by low power irradiation ``in situ''. The case (i) deals with surface evaporation and boiling processes in presence of superheating. A computer simulation model of thermal sputtering by vapor bubble nucleation in molten phase shows that non-equilibrium processing enables the rise of large surface temperature gradients in the boiling layer and the possibility of sub-surface temperature maximum. The case (ii) concerns the heterogeneous welding of Cu and AISI 304L stainless steel plates by electron beam irradiation. Microstructural investigation of the molten zone has shown that dwell times of the order of 10-1-10-3 s, consistent with moderate cooling rates in the range 10^3-10^5 K/s, entail the formation of metastable Cu-Fe phases. The case (iii) concerns electron beam welding and post-welding treatments of 2219 Al base alloy. Electron microscopy and positron annihilation have explained why post-weld heat transients induced by low power irradiation of specimens in the as welded condition enable ageing effects usually expected after some hours of treatment in furnace. The problem of microstructural instability is particularly significant for a correct design of components manufactured with high power beam technologies and subjected to severe acceptance standards to ensure advanced performances during service life.
Non-equilibrium dynamics of glass-forming liquid mixtures
NASA Astrophysics Data System (ADS)
Sánchez-Díaz, Luis Enrique; Lázaro-Lázaro, Edilio; Olais-Govea, José Manuel; Medina-Noyola, Magdaleno
2014-06-01
The non-equilibrium self-consistent generalized Langevin equation theory of irreversible processes in glass-forming liquids [P. Ramírez-González and M. Medina-Noyola, Phys. Rev. E 82, 061503 (2010)] is extended here to multi-component systems. The resulting theory describes the statistical properties of the instantaneous local particle concentration profiles nα(r, t) of species α in terms of the coupled time-evolution equations for the mean value overline{n}_α ({r},t) and for the covariance σ _{α β }({r},{r}^' };t)equiv overline{δ n_α ({r},t)δ n_β ({r}^' },t)} of the fluctuations δ n_α ({r},t) = n_α ({r},t)- overline{n}_α ({r},t). As in the monocomponent case, these two coarse-grained equations involve a local mobility function bα(r, t) for each species, written in terms of the memory function of the two-time correlation function C_{α β }({r},{r}^' };t,t^' }) equiv overline{δ n_α ({r},t)δ n_β ({r}^' },t^' })}. If the system is constrained to remain spatially uniform and subjected to a non-equilibrium preparation protocol described by a given temperature and composition change program T(t) and overline{n}_α (t), these equations predict the irreversible structural relaxation of the partial static structure factors Sαβ(k; t) and of the (collective and self) intermediate scattering functions Fαβ(k, τ; t) and F^S_{α β }(k,τ ;t). We illustrate the applicability of the resulting theory with two examples involving simple model mixtures subjected to an instantaneous temperature quench: an electroneutral binary mixture of equally sized and oppositely charged hard-spheres, and a binary mixture of soft-spheres of moderate size-asymmetry.
THERMAL NON-EQUILIBRIUM REVISITED: A HEATING MODEL FOR CORONAL LOOPS
Lionello, Roberto; Linker, Jon A.; Mikic, Zoran; Winebarger, Amy R.; Mok, Yung E-mail: linkerj@predsci.com E-mail: amy.r.winebarger@nasa.gov
2013-08-20
The location and frequency of events that heat the million-degree corona are still a matter of debate. One potential heating scenario is that the energy release is effectively steady and highly localized at the footpoints of coronal structures. Such an energy deposition drives thermal non-equilibrium solutions in the hydrodynamic equations in longer loops. This heating scenario was considered and discarded by Klimchuk et al. on the basis of their one-dimensional simulations as incapable of reproducing observational characteristics of loops. In this paper, we use three-dimensional simulations to generate synthetic emission images, from which we select and analyze six loops. The main differences between our model and that of Klimchuk et al. concern (1) dimensionality, (2) resolution, (3) geometrical properties of the loops, (4) heating function, and (5) radiative function. We find evidence, in this small set of simulated loops, that the evolution of the light curves, the variation of temperature along the loops, the density profile, and the absence of small-scale structures are compatible with the characteristics of observed loops. We conclude that quasi-steady footpoint heating that drives thermal non-equilibrium solutions cannot yet be ruled out as a viable heating scenario for EUV loops.
Study of a non-equilibrium plasma pinch with application for microwave generation
NASA Astrophysics Data System (ADS)
Al Agry, Ahmad Farouk
The Non-Equilibrium Plasma Pinch (NEPP), also known as the Dense Plasma Focus (DPF) is well known as a source of energetic ions, relativistic electrons and neutrons as well as electromagnetic radiation extending from the infrared to X-ray. In this dissertation, the operation of a 15 kJ, Mather type, NEPP machine is studied in detail. A large number of experiments are carried out to tune the machine parameters for best performance using helium and hydrogen as filling gases. The NEPP machine is modified to be able to extract the copious number of electrons generated at the pinch. A hollow anode with small hole at the flat end, and a mock magnetron without biasing magnetic field are built. The electrons generated at the pinch are very difficult to capture, therefore a novel device is built to capture and transport the electrons from the pinch to the magnetron. The novel cup-rod-needle device successfully serves the purpose to capture and transport electrons to monitor the pinch current. Further, the device has the potential to field emit charges from its needle end acting as a pulsed electron source for other devices such as the magnetron. Diagnostics tools are designed, modeled, built, calibrated, and implemented in the machine to measure the pinch dynamics. A novel, UNLV patented electromagnetic dot sensors are successfully calibrated, and implemented in the machine. A new calibration technique is developed and test stands designed and built to measure the dot's ability to track the impetus signal over its dynamic range starting and ending in the noise region. The patented EM-dot sensor shows superior performance over traditional electromagnetic sensors, such as Rogowski coils. On the other hand, the cup-rod structure, when grounded on the rod side, serves as a diagnostic tool to monitor the pinch current by sampling the actual current, a quantity that has been always very challenging to measure without perturbing the pinch. To the best of our knowledge, this method
Stability of high-speed boundary layers in oxygen including chemical non-equilibrium effects
NASA Astrophysics Data System (ADS)
Klentzman, Jill; Tumin, Anatoli
2013-11-01
The stability of high-speed boundary layers in chemical non-equilibrium is examined. A parametric study varying the edge temperature and the wall conditions is conducted for boundary layers in oxygen. The edge Mach number and enthalpy ranges considered are relevant to the flight conditions of reusable hypersonic cruise vehicles. Both viscous and inviscid stability formulations are used and the results compared to gain insight into the effects of viscosity and thermal conductivity on the stability. It is found that viscous effects have a strong impact on the temperature and mass fraction perturbations in the critical layer and in the viscous sublayer near the wall. Outside of these areas, the perturbations closely match in the viscous and inviscid models. The impact of chemical non-equilibrium on the stability is investigated by analyzing the effects of the chemical source term in the stability equations. The chemical source term is found to influence the growth rate of the second Mack mode instability but not have much of an effect on the mass fraction eigenfunction for the flow parameters considered. This work was supported by the AFOSR/NASA/National Center for Hypersonic Laminar-Turbulent Transition Research.
An Initial Non-Equilibrium Porous-Media Model for CFD Simulation of Stirling Regenerators
NASA Technical Reports Server (NTRS)
Tew, Roy; Simon, Terry; Gedeon, David; Ibrahim, Mounir; Rong, Wei
2006-01-01
The objective of this paper is to define empirical parameters (or closwre models) for an initial thermai non-equilibrium porous-media model for use in Computational Fluid Dynamics (CFD) codes for simulation of Stirling regenerators. The two CFD codes currently being used at Glenn Research Center (GRC) for Stirling engine modeling are Fluent and CFD-ACE. The porous-media models available in each of these codes are equilibrium models, which assmne that the solid matrix and the fluid are in thermal equilibrium at each spatial location within the porous medium. This is believed to be a poor assumption for the oscillating-flow environment within Stirling regenerators; Stirling 1-D regenerator models, used in Stirling design, we non-equilibrium regenerator models and suggest regenerator matrix and gas average temperatures can differ by several degrees at a given axial location end time during the cycle. A NASA regenerator research grant has been providing experimental and computational results to support definition of various empirical coefficients needed in defining a noa-equilibrium, macroscopic, porous-media model (i.e., to define "closure" relations). The grant effort is being led by Cleveland State University, with subcontractor assistance from the University of Minnesota, Gedeon Associates, and Sunpower, Inc. Friction-factor and heat-transfer correlations based on data taken with the NASAlSunpower oscillating-flow test rig also provide experimentally based correlations that are useful in defining parameters for the porous-media model; these correlations are documented in Gedeon Associates' Sage Stirling-Code Manuals. These sources of experimentally based information were used to define the following terms and parameters needed in the non-equilibrium porous-media model: hydrodynamic dispersion, permeability, inertial coefficient, fluid effective thermal conductivity (including themal dispersion and estimate of tortuosity effects}, and fluid-solid heat transfer
Numerical Simulation of Non-Equilibrium Plasma Discharge for High Speed Flow Control
NASA Astrophysics Data System (ADS)
Balasubramanian, Ramakrishnan; Anandhanarayanan, Karupannasamy; Krishnamurthy, Rajah; Chakraborty, Debasis
2016-06-01
Numerical simulation of hypersonic flow control using plasma discharge technique is carried out using an in-house developed code CERANS-TCNEQ. The study is aimed at demonstrating a proof of concept futuristic aerodynamic flow control device. The Kashiwa Hypersonic and High Temperature wind tunnel study of plasma discharge over a flat plate had been considered for numerical investigation. The 7-species, 18-reaction thermo-chemical non-equilibrium, two-temperature air-chemistry model due Park is used to model the weakly ionized flow. Plasma discharge is modeled as Joule heating source terms in both the translation-rotational and vibrational energy equations. Comparison of results for plasma discharge at Mach 7 over a flat plate with the reference data reveals that the present study is able to mimic the exact physics of complex flow such as formation of oblique shock wave ahead of the plasma discharge region with a resultant rise in surface pressure and vibrational temperature up to 7000 K demonstrating the use of non-equilibrium plasma discharge for flow control at hypersonic speeds.
Non-equilibrium Aspects of Quantum Integrable Systems
NASA Astrophysics Data System (ADS)
Andrei, Natan
The study of non-equilibrium dynamics of interacting many body systems is currently one of the main challenges of modern condensed matter physics, driven by the spectacular progress in the ability to create experimental systems - trapped cold atomic gases are a prime example - that can be isolated from their environment and be highly controlled. Many old and new questions can be addressed: thermalization of isolated systems, nonequilibrium steady states, the interplay between non equilibrium currents and strong correlations, quantum phase transitions in time, universality among others. In this talk I will describe nonequilibrium quench dynamics in integrable quantum systems. I'll discuss the time evolution of the Lieb-Liniger system, a gas of interacting bosons moving on the continuous infinite line and interacting via a short range potential. Considering a finite number of bosons on the line we find that for any value of repulsive coupling the system asymptotes towards a strongly repulsive gas for any initial state, while for an attractive coupling, the system forms a maximal bound state that dominates at longer times. In the thermodynamic limit -with the number of bosons and the system size sent to infinity at a constant density and the long time limit taken subsequently- I'll show that the density and density-density correlation functions for strong but finite positive coupling are described by GGE for translationally invariant initial states with short range correlations. As examples I'll discuss quenches from a Mott insulator initial state or a Newton's Cradle. Then I will show that if the initial state is strongly non translational invariant, e.g. a domain wall configuration, the system does not equilibrate but evolves into a nonequilibrium steady state (NESS). A related NESS arises when the quench consists of coupling a quantum dot to two leads held at different chemical potential, leading in the long time limit to a steady state current. Time permitting I
Equilibrium and non-equilibrium dynamics simultaneously operate in the Galápagos islands.
Valente, Luis M; Phillimore, Albert B; Etienne, Rampal S
2015-08-01
Island biotas emerge from the interplay between colonisation, speciation and extinction and are often the scene of spectacular adaptive radiations. A common assumption is that insular diversity is at a dynamic equilibrium, but for remote islands, such as Hawaii or Galápagos, this idea remains untested. Here, we reconstruct the temporal accumulation of terrestrial bird species of the Galápagos using a novel phylogenetic method that estimates rates of biota assembly for an entire community. We show that species richness on the archipelago is in an ascending phase and does not tend towards equilibrium. The majority of the avifauna diversifies at a slow rate, without detectable ecological limits. However, Darwin's finches form an exception: they rapidly reach a carrying capacity and subsequently follow a coalescent-like diversification process. Together, these results suggest that avian diversity of remote islands is rising, and challenge the mutual exclusivity of the non-equilibrium and equilibrium ecological paradigms.
Equilibrium and non-equilibrium dynamics simultaneously operate in the Galápagos islands.
Valente, Luis M; Phillimore, Albert B; Etienne, Rampal S
2015-08-01
Island biotas emerge from the interplay between colonisation, speciation and extinction and are often the scene of spectacular adaptive radiations. A common assumption is that insular diversity is at a dynamic equilibrium, but for remote islands, such as Hawaii or Galápagos, this idea remains untested. Here, we reconstruct the temporal accumulation of terrestrial bird species of the Galápagos using a novel phylogenetic method that estimates rates of biota assembly for an entire community. We show that species richness on the archipelago is in an ascending phase and does not tend towards equilibrium. The majority of the avifauna diversifies at a slow rate, without detectable ecological limits. However, Darwin's finches form an exception: they rapidly reach a carrying capacity and subsequently follow a coalescent-like diversification process. Together, these results suggest that avian diversity of remote islands is rising, and challenge the mutual exclusivity of the non-equilibrium and equilibrium ecological paradigms. PMID:26105791
NASA Astrophysics Data System (ADS)
Viktorov, Mikhail; Golubev, Sergey; Mansfeld, Dmitry; Vodopyanov, Alexander; Zaitsev, Valery
2016-04-01
Plasma instabilities in magnetic traps on the Sun are the sources of powerful broadband radio emission (the so-called type IV bursts) which is interpreted as the excitation of plasma waves by fast electrons in the upper hybrid resonance frequency followed by transformation in electromagnetic waves. In the case of double plasma resonance condition when the frequency of the upper hybrid resonance coincides with one of the electron gyrofrequency harmonics the instability increment of plasma waves is greatly increased. This leads to the appearance of bright narrow-band radio emission near the harmonics of the electron gyrofrequency - the so-called zebra patterns. With the use of non-equilibrium mirror-confined plasma produced by the electron cyclotron resonance (ECR) discharge we provide the possibility to study plasma instabilities under double plasma resonance condition in the laboratory. In the experiment such conditions are fulfilled just after ECR heating switch-off, i.e. in the very beginning of a dense plasma decay phase. The observed instability is accompanied by a pulse-periodic generation of a powerful electromagnetic radiation at a frequency close to the upper hybrid resonance frequency and a second harmonic of the electron gyrofrequency, and synchronous precipitations of fast electrons from the trap ends. It is shown that the observed instability is due to the excitation of plasma waves at a double plasma resonance in decaying plasma of the ECR discharge. Possible manifestations of double plasma resonance effect are not rare in astrophysical plasmas. The phenomenon of zebra pattern is observed not only on the Sun, but in the decametric radiation of the Jupiter, kilometric radiation of the Earth and even in the radio emissions of pulsars. Thus, verification of the effect of double plasma resonance in a laboratory plasma experiments is a very relevant task.
Non-equilibrium control of complex solids by nonlinear phononics
NASA Astrophysics Data System (ADS)
Mankowsky, Roman; Först, Michael; Cavalleri, Andrea
2016-06-01
We review some recent advances in the use of optical fields at terahertz frequencies to drive the lattice of complex materials. We will focus on the control of low energy collective properties of solids, which emerge on average when a high frequency vibration is driven and a new crystal structure induced. We first discuss the fundamentals of these lattice rearrangements, based on how anharmonic mode coupling transforms an oscillatory motion into a quasi-static deformation of the crystal structure. We then discuss experiments, in which selectively changing a bond angle turns an insulator into a metal, accompanied by changes in charge, orbital and magnetic order. We then address the case of light induced non-equilibrium superconductivity, a mysterious phenomenon observed in some cuprates and molecular materials when certain lattice vibrations are driven. Finally, we show that the dynamics of electronic and magnetic phase transitions in complex-oxide heterostructures follow distinctly new physical pathways in case of the resonant excitation of a substrate vibrational mode.
Non-Equilibrium Water-Glassy Polymer Dynamics
NASA Astrophysics Data System (ADS)
Davis, Eric; Minelli, Matteo; Baschetti, Marco; Sarti, Giulio; Elabd, Yossef
2012-02-01
For many applications (e.g., medical implants, packaging), an accurate assessment and fundamental understanding of the dynamics of water-glassy polymer interactions is of great interest. In this study, sorption and diffusion of pure water in several glassy polymers films, such as poly(styrene) (PS), poly(methyl methacrylate) (PMMA), poly(lactide) (PLA), were measured over a wide range of vapor activities and temperatures using several experimental techniques, including quartz spring microbalance (QSM), quartz crystal microbalance (QCM), and time-resolved Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy. Non-Fickian behavior (diffusion-relaxation phenomena) was observed by all three techniques, while FTIR-ATR spectroscopy also provides information about the distribution of the states of water and water transport mechanisms on a molecular-level. Specifically, the states of water are significantly different in PS compared to PMMA and PLA. Additionally, a purely predictive non-equilibrium lattice fluid (NELF) model was applied to predict the sorption isotherms of water in these glassy polymers.
Non-Equilibrium Turbulence and Two-Equation Modeling
NASA Technical Reports Server (NTRS)
Rubinstein, Robert
2011-01-01
Two-equation turbulence models are analyzed from the perspective of spectral closure theories. Kolmogorov theory provides useful information for models, but it is limited to equilibrium conditions in which the energy spectrum has relaxed to a steady state consistent with the forcing at large scales; it does not describe transient evolution between such states. Transient evolution is necessarily through nonequilibrium states, which can only be found from a theory of turbulence evolution, such as one provided by a spectral closure. When the departure from equilibrium is small, perturbation theory can be used to approximate the evolution by a two-equation model. The perturbation theory also gives explicit conditions under which this model can be valid, and when it will fail. Implications of the non-equilibrium corrections for the classic Tennekes-Lumley balance in the dissipation rate equation are drawn: it is possible to establish both the cancellation of the leading order Re1/2 divergent contributions to vortex stretching and enstrophy destruction, and the existence of a nonzero difference which is finite in the limit of infinite Reynolds number.
A probability theory for non-equilibrium gravitational systems
NASA Astrophysics Data System (ADS)
Peñarrubia, Jorge
2015-08-01
This paper uses dynamical invariants to describe the evolution of collisionless systems subject to time-dependent gravitational forces without resorting to maximum-entropy probabilities. We show that collisionless relaxation can be viewed as a special type of diffusion process in the integral-of-motion space. In time-varying potentials with a fixed spatial symmetry the diffusion coefficients are closely related to virial quantities, such as the specific moment of inertia, the virial factor and the mean kinetic and potential energy of microcanonical particle ensembles. The non-equilibrium distribution function is found by convolving the initial distribution function with the Green function that solves Einstein's equation for freely diffusing particles. Such a convolution also yields a natural solution to the Fokker-Planck equations in the energy space. Our mathematical formalism can be generalized to potentials with a time-varying symmetry, where diffusion extends over multiple dimensions of the integral-of-motion space. The new probability theory is in many ways analogous to stochastic calculus, with two significant differences: (i) the equations of motion that govern the trajectories of particles are fully deterministic, and (ii) the diffusion coefficients can be derived self-consistently from microcanonical phase-space averages without relying on ergodicity assumptions. For illustration we follow the cold collapse of N-body models in a time-dependent logarithmic potential. Comparison between the analytical and numerical results shows excellent agreement in regions where the potential evolution does not depart too strongly from the adiabatic regime.
Non-equilibrium plasma prevention of Schistosoma japonicum transmission
Wang, Xing-Quan; Wang, Feng-Peng; Chen, Wei; Huang, Jun; Bazaka, Kateryna; Ostrikov, Kostya (Ken)
2016-01-01
Schistosoma japonicum is a widespread human and animal parasite that causes intestinal and hepatosplenic schistosomiasis linked to colon, liver and bladder cancers, and anemia. Estimated 230 million people are currently infected with Schistosoma spp, with 779 million people at risk of contracting the parasite. Infection occurs when a host comes into contact with cercariae, a planktonic larval stage of the parasite, and can be prevented by inactivating the larvae, commonly by chemical treatment. We investigated the use of physical non-equilibrium plasma generated at atmospheric pressure using custom-made dielectric barrier discharge reactor to kill S. japonicum cercariae. Survival rate decreased with treatment time and applied power. Plasmas generated in O2 and air gas discharges were more effective in killing S. japonicum cercariae than that generated in He, which is directly related to the mechanism by which cercariae are inactivated. Reactive oxygen species, such as O atoms, abundant in O2 plasma and NO in air plasma play a major role in killing of S. japonicum cercariae via oxidation mechanisms. Similar level of efficacy is also shown for a gliding arc discharge plasma jet generated in ambient air, a system that may be more appropriate for scale-up and integration into existing water treatment processes. PMID:27739459
Non-equilibrium Transport in Carbon based Adsorbate Systems
NASA Astrophysics Data System (ADS)
Fürst, Joachim; Brandbyge, Mads; Stokbro, Kurt; Jauho, Antti-Pekka
2007-03-01
We have used the Atomistix Tool Kit(ATK) and TranSIESTA[1] packages to investigate adsorption of iron atoms on a graphene sheet. The technique of both codes is based on density functional theory using local basis sets[2], and non-equilibrium Green's functions (NEGF) to calculate the charge distribution under external bias. Spin dependent electronic structure calculations are performed for different iron coverages. These reveal adsorption site dependent charge transfer from iron to graphene leading to screening effects. Transport calculations show spin dependent scattering of the transmission which is analysed obtaining the transmission eigenchannels for each spin type. The phenomena of electromigration of iron in these systems at finite bias will be discussed, estimating the so-called wind force from the reflection[3]. [1] M. Brandbyge, J.-L. Mozos, P. Ordejon, J. Taylor, and K. Stokbro. Physical Review B (Condensed Matter and Materials Physics), 65(16):165401/11-7, 2002. [2] Jose M. Soler, Emilio Artacho, Julian D. Gale, Alberto Garcia, Javier Junquera, Pablo Ordejon, and Daniel Sanchez-Portal. Journal of Physics Condensed Matter, 14(11):2745-2779, 2002. [3] Sorbello. Theory of electromigration. Solid State Physics, 1997.
Non-Equilibrium Properties from Equilibrium Free Energy Calculations
NASA Technical Reports Server (NTRS)
Pohorille, Andrew; Wilson, Michael A.
2012-01-01
Calculating free energy in computer simulations is of central importance in statistical mechanics of condensed media and its applications to chemistry and biology not only because it is the most comprehensive and informative quantity that characterizes the eqUilibrium state, but also because it often provides an efficient route to access dynamic and kinetic properties of a system. Most of applications of equilibrium free energy calculations to non-equilibrium processes rely on a description in which a molecule or an ion diffuses in the potential of mean force. In general case this description is a simplification, but it might be satisfactorily accurate in many instances of practical interest. This hypothesis has been tested in the example of the electrodiffusion equation . Conductance of model ion channels has been calculated directly through counting the number of ion crossing events observed during long molecular dynamics simulations and has been compared with the conductance obtained from solving the generalized Nernst-Plank equation. It has been shown that under relatively modest conditions the agreement between these two approaches is excellent, thus demonstrating the assumptions underlying the diffusion equation are fulfilled. Under these conditions the electrodiffusion equation provides an efficient approach to calculating the full voltage-current dependence routinely measured in electrophysiological experiments.
Interaction of non-equilibrium oxygen plasma with sintered graphite
NASA Astrophysics Data System (ADS)
Cvelbar, Uroš
2013-03-01
Samples made from sintered graphite with grain size of about 10 μm were exposed to highly non-equilibrium oxygen plasma created in a borosilicate glass tube by an electrodeless RF discharge. The density of charged particles was about 7 × 1015 m-3 and the neutral oxygen atom density 6 × 1021 m-3. The sample temperature was determined by a calibrated IR detector while the surface modifications were quantified by XPS and water drop techniques. The sample surface was rapidly saturated with carbonyl groups. Prolonged treatment of samples caused a decrease in concentration of the groups what was explained by thermal destruction. Therefore, the created functional groups were temperature dependent. The heating of samples resulted in extensive chemical interaction between the O atoms and samples what was best monitored by decreasing of the O atom density with increasing sample temperature. The saturation with functional groups could be restored only after cooling down of the samples and repeated short plasma treatment at low temperature.
NON-EQUILIBRIUM IONIZATION IN THE BIFROST STELLAR ATMOSPHERE CODE
Olluri, K.; Gudiksen, B. V.; Hansteen, V. H.
2013-03-15
The chromosphere and transition region have for the last 20 years been known to be quite dynamic layers of the solar atmosphere, characterized by timescales shorter than the ionization equilibrium timescales of many of the ions dominating emission in these regions. Due to the fast changes in the properties of the atmosphere, long ionization and recombination times can lead these ions to being found far from their equilibrium temperatures. A number of the spectral lines that we observe can therefore not be expected a priori to reflect information about local quantities such as the density or temperature, and interpreting observations requires numerical modeling. Modeling the ionization balance is computationally expensive and has earlier only been done in one dimension. However, one-dimensional models can primarily be used to investigate the possible importance of a physical effect, but cannot verify or disprove the importance of that effect in the fully three-dimensional solar atmosphere. Here, using the atomic database package DIPER, we extend one-dimensional methods and implement a solver for the rate equations of the full three-dimensional problem, using the numerical code Bifrost. We present our implementation and report on a few test cases. We also report on studies of the important C IV and Fe XII ions in a semi-realistic two-dimensional solar atmosphere model, focusing on differences between statistical equilibrium and non-equilibrium ionization results.
Non-equilibrium Warm Dense Gold: Experiments and Simulations
NASA Astrophysics Data System (ADS)
Ng, Andrew
2015-11-01
This talk is an overview of a series of studies of non-equilibrium Warm Dense Matter using a broad range of measured properties of a single material, namely Au, as comprehensive benchmarks for theory. The measurements are made in fs-laser pump-probe experiments. For understanding lattice stability, our investigation reveals a solid phase at high energy density. This leads to the calculation of lattice dynamics using MD simulations and phonon hardening in DFT-MD simulations. For understanding electron transport in two-temperature states, AC conductivity is used to evaluate DFT-MD and Kubo-Greenwood calculations while DC conductivity is used to test Ziman calculations in a DFT average atom model. The electron density is also used to assess electronic structure calculations in DFT simulations. In our latest study of electron kinetics in states with a non-Fermi-Dirac distribution, three-body recombination is found to have a significant effect on electron thermalizaiton time. This is driving an effort to develop electron kinetics simulations using the Boltzmann equation method.
Non-equilibrium plasma prevention of Schistosoma japonicum transmission
NASA Astrophysics Data System (ADS)
Wang, Xing-Quan; Wang, Feng-Peng; Chen, Wei; Huang, Jun; Bazaka, Kateryna; Ostrikov, Kostya (Ken)
2016-10-01
Schistosoma japonicum is a widespread human and animal parasite that causes intestinal and hepatosplenic schistosomiasis linked to colon, liver and bladder cancers, and anemia. Estimated 230 million people are currently infected with Schistosoma spp, with 779 million people at risk of contracting the parasite. Infection occurs when a host comes into contact with cercariae, a planktonic larval stage of the parasite, and can be prevented by inactivating the larvae, commonly by chemical treatment. We investigated the use of physical non-equilibrium plasma generated at atmospheric pressure using custom-made dielectric barrier discharge reactor to kill S. japonicum cercariae. Survival rate decreased with treatment time and applied power. Plasmas generated in O2 and air gas discharges were more effective in killing S. japonicum cercariae than that generated in He, which is directly related to the mechanism by which cercariae are inactivated. Reactive oxygen species, such as O atoms, abundant in O2 plasma and NO in air plasma play a major role in killing of S. japonicum cercariae via oxidation mechanisms. Similar level of efficacy is also shown for a gliding arc discharge plasma jet generated in ambient air, a system that may be more appropriate for scale-up and integration into existing water treatment processes.
Speeding Up Calculations Of The Non-equilibrium Ionization Model
NASA Astrophysics Data System (ADS)
Ji, Li; Noble, M.; Schulz, N. S.; Nowak, M. A.; Marshall, H. L.
2008-03-01
By taking advantage of the atomic data and physics from the equilibrium photoionization model of XSTAR, we are extending our non-equilibrium collisional ionization code to photoionized plasmas. The expanded model will allow us to study processes in a wide range of astrophysical scenarios -- such as colliding winds in X-ray binaries, outflows in AGNs, and shock flows in the IGM, but presents significant challenges. Chief among these are that the new model is expensive to compute and difficult to compare directly with HETG observations. We discuss how parallelism and modular software techniques are being brought to bear on these problems, in the context of several applications: (1) emission measurement analysis for the accretion disk corona of HerX-1, using XSTAR within the Parallel Virtual Machine; (2) using ISIS for direct ionization analysis and line diagnostics of the plane shock model, via our dynamically loadable interface to selected routines from the XSPEC vpshock model; and (3) computing atomic rates directly in ISIS by way of our dynamically loadable XSTAR module.
Radiation attenuation gauge with magnetically coupled source
Wallace, Steven A.
1978-01-01
A radiaton attenuation gauge for measuring thickness and density of a material comprises, in combination, a source of gamma radiation contained within a housing comprising magnetic or ferromagnetic material, and a means for measuring the intensity of gamma radiation. The measuring means has an aperture and magnetic means disposed adjacent to the aperture for attracting and holding the housed source in position before the aperture. The material to be measured is disposed between the source and the measuring means.
Doses from Medical Radiation Sources
... radiation dosimetry. Continuing Medical Education Article, Journal of Nuclear Medicine 41(5):863â€“873; 2000. © 2016 Health Physics Society Site Map | Privacy Statement | Disclaimer | Webmaster
New Simulator for Non-Equilibrium Modeling of Hydrate Reservoirs
NASA Astrophysics Data System (ADS)
Kvamme, B.; Qorbani Nashaqi, K.; Jemai, K.; Vafaei, M.
2014-12-01
Due to Gibbs phase rule and combination of first and second law of thermodynamics, hydrate in nature cannot be in equilibrium since they come from different parent phases. In this system hydrate formation and dissociation is affected by local variables such as pressure, temperature and composition with mass and energy transport restrictions. Available simulators have attempted to model hydrate phase transition as an equilibrium reaction. Although those which treated the processes of formation and dissociation as kinetics used model of Kim and Bishnoi based on laboratory PVT experiment, and consequently hard to accept up scaling to real reservoirs condition. Additionally, they merely check equilibrium in terms of pressure and temperature projections and disregard thermodynamic requirements for equilibrium especially along axes of concentrations in phases. Non-equilibrium analysis of hydrate involves putting aside all the phase transitions which are not possible and use kinetic evaluation to measure phase transitions progress in each grid block for each time step. This procedure is Similar to geochemical reservoir simulators logic. As a result RetrasoCodeBright has been chosen as hydrate reservoir simulator and our work involves extension of this code. RetrasoCodeBright (RCB) is able to handle competing processes of formation and dissociation of hydrates as pseudo reactions at each node and each time step according to the temperature, pressure and concentration. Hydrates can therefore be implemented into the structure as pseudo minerals, with appropriate kinetic models. In order to implement competing nature of phase transition kinetics of hydrate formation, we use classical nucleation theory based on Kvamme et al. as a simplified model inside RCB and use advanced theories to fit parameters for the model (PFT). Hydrate formation and dissociation can directly be observed through porosity changes in the specific areas of the porous media. In this work which is in
Perturbative Calculation of Quasi-Potential in Non-equilibrium Diffusions: A Mean-Field Example
NASA Astrophysics Data System (ADS)
Bouchet, Freddy; Gawȩdzki, Krzysztof; Nardini, Cesare
2016-06-01
In stochastic systems with weak noise, the logarithm of the stationary distribution becomes proportional to a large deviation rate function called the quasi-potential. The quasi-potential, and its characterization through a variational problem, lies at the core of the Freidlin-Wentzell large deviations theory (Freidlin and Wentzell, Random perturbations of dynamical systems, 2012). In many interacting particle systems, the particle density is described by fluctuating hydrodynamics governed by Macroscopic Fluctuation Theory (Bertini et al.,
Step-wise pulling protocols for non-equilibrium dynamics
NASA Astrophysics Data System (ADS)
Ngo, Van Anh
The fundamental laws of thermodynamics and statistical mechanics, and the deeper understandings of quantum mechanics have been rebuilt in recent years. It is partly because of the increasing power of computing resources nowadays, that allow shedding direct insights into the connections among the thermodynamics laws, statistical nature of our world, and the concepts of quantum mechanics, which have not yet been understood. But mostly, the most important reason, also the ultimate goal, is to understand the mechanisms, statistics and dynamics of biological systems, whose prevailing non-equilibrium processes violate the fundamental laws of thermodynamics, deviate from statistical mechanics, and finally complicate quantum effects. I believe that investigations of the fundamental laws of non-equilibrium dynamics will be a frontier research for at least several more decades. One of the fundamental laws was first discovered in 1997 by Jarzynski, so-called Jarzynski's Equality. Since then, different proofs, alternative descriptions of Jarzynski's Equality, and its further developments and applications have been quickly accumulated. My understandings, developments and applications of an alternative theory on Jarzynski's Equality form the bulk of this dissertation. The core of my theory is based on stepwise pulling protocols, which provide deeper insight into how fluctuations of reaction coordinates contribute to free-energy changes along a reaction pathway. We find that the most optimal pathways, having the largest contribution to free-energy changes, follow the principle of detailed balance. This is a glimpse of why the principle of detailed balance appears so powerful for sampling the most probable statistics of events. In a further development on Jarzynski's Equality, I have been trying to use it in the formalism of diagonal entropy to propose a way to extract useful thermodynamic quantities such temperature, work and free-energy profiles from far
Upwind MacCormack Euler solver with non-equilibrium chemistry
NASA Technical Reports Server (NTRS)
Sherer, Scott E.; Scott, James N.
1993-01-01
A computer code, designated UMPIRE, is currently under development to solve the Euler equations in two dimensions with non-equilibrium chemistry. UMPIRE employs an explicit MacCormack algorithm with dissipation introduced via Roe's flux-difference split upwind method. The code also has the capability to employ a point-implicit methodology for flows where stiffness is introduced through the chemical source term. A technique consisting of diagonal sweeps across the computational domain from each corner is presented, which is used to reduce storage and execution requirements. Results depicting one dimensional shock tube flow for both calorically perfect gas and thermally perfect, dissociating nitrogen are presented to verify current capabilities of the program. Also, computational results from a chemical reactor vessel with no fluid dynamic effects are presented to check the chemistry capability and to verify the point implicit strategy.
Microscopic Simulation and Macroscopic Modeling for Thermal and Chemical Non-Equilibrium
NASA Technical Reports Server (NTRS)
Liu, Yen; Panesi, Marco; Vinokur, Marcel; Clarke, Peter
2013-01-01
This paper deals with the accurate microscopic simulation and macroscopic modeling of extreme non-equilibrium phenomena, such as encountered during hypersonic entry into a planetary atmosphere. The state-to-state microscopic equations involving internal excitation, de-excitation, dissociation, and recombination of nitrogen molecules due to collisions with nitrogen atoms are solved time-accurately. Strategies to increase the numerical efficiency are discussed. The problem is then modeled using a few macroscopic variables. The model is based on reconstructions of the state distribution function using the maximum entropy principle. The internal energy space is subdivided into multiple groups in order to better describe the non-equilibrium gases. The method of weighted residuals is applied to the microscopic equations to obtain macroscopic moment equations and rate coefficients. The modeling is completely physics-based, and its accuracy depends only on the assumed expression of the state distribution function and the number of groups used. The model makes no assumption at the microscopic level, and all possible collisional and radiative processes are allowed. The model is applicable to both atoms and molecules and their ions. Several limiting cases are presented to show that the model recovers the classical twotemperature models if all states are in one group and the model reduces to the microscopic equations if each group contains only one state. Numerical examples and model validations are carried out for both the uniform and linear distributions. Results show that the original over nine thousand microscopic equations can be reduced to 2 macroscopic equations using 1 to 5 groups with excellent agreement. The computer time is decreased from 18 hours to less than 1 second.
TLD response to non-radiation sources
Ong, A. )
1985-10-01
A study was performed at the San Onofre Nuclear Generating Station (SONGS) to evaluate the response of personnel TLD badges to non-radiation sources commonly encountered at the station. The TLD normally used at SONGS is the four-element Panasonic Model UD802-AS2 shown on the next page. This paper reports that the non-radiation sources employed in the study consisted of two different cleaning agents, sunlight, and electric arc welding.
NASA Astrophysics Data System (ADS)
Kawakatsu, T.; Matsuyama, A.; Ohta, T.; Tanaka, H.; Tanaka, S.
2011-07-01
Soft matter is a rapidly growing interdisciplinary research field covering a range of subject areas including physics, chemistry, biology, mathematics and engineering. Some of the important universal features of these materials are their mesoscopic structures and their dynamics. Due to the existence of such large-scale structures, which nevertheless exhibit interactions of the order of the thermal energy, soft matter can readily be taken out of equilibrium by imposing a weak external field such as an electric field, a mechanical stress or a shear flow. The importance of the coexistence of microscopic molecular dynamics and the mesoscopic/macroscopic structures and flows requires us to develop hierarchical approaches to understand the nonlinear and nonequilibrium phenomena, which is one of the central issues of current soft matter research. This special section presents selected contributions from the 'International Symposium on Non-Equilibrium Soft Matter 2010' held from 17-20 August 2010 in Nara, Japan, which aimed to describe recent advances in soft matter research focusing especially on its nonequilibrium aspects. The topics discussed cover statics and dynamics of a wide variety of materials ranging from traditional soft matter like polymers, gels, emulsions, liquid crystals and colloids to biomaterials such as biopolymers and biomembranes. Among these studies, we highlighted the physics of biomembranes and vesicles, which has attracted great attention during the last decade; we organized a special session for this active field. The work presented in this issue deals with (1) structure formation in biomembranes and vesicles, (2) rheology of polymers and gels, (3) mesophases in block copolymers, (4) mesoscopic structures in liquid crystals and ionic liquids, and (5) nonequilibrium dynamics. This symposium was organized as part of a research project supported by the Grant-in-Aid for the priority area 'Soft Matter Physics' (2006-2010) from the Ministry of Education
NASA Astrophysics Data System (ADS)
Kawakatsu, T.; Matsuyama, A.; Ohta, T.; Tanaka, H.; Tanaka, S.
2011-07-01
Soft matter is a rapidly growing interdisciplinary research field covering a range of subject areas including physics, chemistry, biology, mathematics and engineering. Some of the important universal features of these materials are their mesoscopic structures and their dynamics. Due to the existence of such large-scale structures, which nevertheless exhibit interactions of the order of the thermal energy, soft matter can readily be taken out of equilibrium by imposing a weak external field such as an electric field, a mechanical stress or a shear flow. The importance of the coexistence of microscopic molecular dynamics and the mesoscopic/macroscopic structures and flows requires us to develop hierarchical approaches to understand the nonlinear and nonequilibrium phenomena, which is one of the central issues of current soft matter research. This special section presents selected contributions from the 'International Symposium on Non-Equilibrium Soft Matter 2010' held from 17-20 August 2010 in Nara, Japan, which aimed to describe recent advances in soft matter research focusing especially on its nonequilibrium aspects. The topics discussed cover statics and dynamics of a wide variety of materials ranging from traditional soft matter like polymers, gels, emulsions, liquid crystals and colloids to biomaterials such as biopolymers and biomembranes. Among these studies, we highlighted the physics of biomembranes and vesicles, which has attracted great attention during the last decade; we organized a special session for this active field. The work presented in this issue deals with (1) structure formation in biomembranes and vesicles, (2) rheology of polymers and gels, (3) mesophases in block copolymers, (4) mesoscopic structures in liquid crystals and ionic liquids, and (5) nonequilibrium dynamics. This symposium was organized as part of a research project supported by the Grant-in-Aid for the priority area 'Soft Matter Physics' (2006-2010) from the Ministry of Education
NASA Astrophysics Data System (ADS)
Temkin, A. Ya.
1989-10-01
The present work is the continuation of the previous works of the author on the non-equilibrium chemical kinetics. The consideration of direct and hot spot reactions provoked by the passage of fast particles through a liquid or solid medium is continued. It is shown that the model of quasi-particles permits us to detect and to consider a kinetic effect of primary fast particle reactions caused by the distribution of target molecules with respect to distance from the primary particle trajectory. It has been found what kinds of chemical kinetic experiments allow us to get rid of this effect to obtain correct values of the reaction elementary act parameters in the condensed phase. Spherical hot spot chemical kinetics of the reaction of two hot diatomic molecules is considered and compared with the one in cylindrical hot spots. It is shown that the creation of spherical hot spots can be stimulated by the addition of atoms having the mass close to that of the primary fast particle. In particular, this can be used to increase the selectivity of the radiation therapy by injection of such atoms to the tumor. Hot atom-polymer segment reaction kinetics in a cylindrical hot spot is considered. The obtained expressions for reaction product yields represent the hot spot contribution to polymer transformations by heavy fast ions. Their possible application to the DNA destruction by hot hydrogen atoms in a hot spot is discussed. Expressions for macroscopic yields of direct and hot spot reactions have been obtained. The hot spot evolution in the presence of laser radiation is considered. Various possibilities of fast particle and laser beams combining irradiation use are considered, especially for the laser material processing and metalworking as well as for the laser medicine.
Atomistic Simulation of Non-Equilibrium Phenomena in Hypersonic Flows
NASA Astrophysics Data System (ADS)
Norman, Paul Erik
The goal of this work is to model the heterogeneous recombination of atomic oxygen on silica surfaces, which is of interest for accurately predicting the heating on vehicles traveling at hypersonic speeds. This is accomplished by creating a finite rate catalytic model, which describes recombination with a set of elementary gas-surface reactions. Fundamental to a description of surface catalytic reactions are the in situ chemical structures on the surface where recombination can occur. Using molecular dynamics simulations with the Reax GSISiO potential, we find that the chemical sites active in direct gas-phase reactions on silica surfaces consist of a small number of specific structures (or defects). The existence of these defects on real silica surfaces is supported by experimental results and the structure and energetics of these defects have been verified with quantum chemical calculations. The reactions in the finite rate catalytic model are based on the interaction of molecular and atomic oxygen with these defects. Trajectory calculations are used to find the parameters in the forward rate equations, while a combination of detailed balance and transition state theory are used to find the parameters in the reverse rate equations. The rate model predicts that the oxygen recombination coefficient is relatively constant at T (300-1000 K), in agreement with experimental results. At T > 1000 K the rate model predicts a drop off in the oxygen recombination coefficient, in disagreement with experimental results, which predict that the oxygen recombination coefficient increases with temperature. A discussion of the possible reasons for this disagreement, including non-adiabatic collision dynamics, variable surface site concentrations, and additional recombination mechanisms is presented. This thesis also describes atomistic simulations with Classical Trajectory Calculation Direction Simulation Monte Carlo (CTC-DSMC), a particle based method for modeling non-equilibrium
Compact sources of EUV radiation
NASA Technical Reports Server (NTRS)
Paresce, F.
1977-01-01
Contrary to classical theoretical expectations extreme ultraviolet emissions from a number of stellar objects have been recently discovered. A combined EUV and optical study of these sources has revealed a wealth of new information on stellar structure and evolution especially for what regards the transition stage between planetary nebulae and white dwarfs. The current status of research in this field is reviewed with emphasis on the impact these observations are having on our view of the later stages of stellar evolution and on the future possibility that could be awaiting a sensitive all sky survey of the EUV spectrum.
Source of Saturnian myriametric radiation
NASA Astrophysics Data System (ADS)
Jones, D.
1983-12-01
The Voyager 1 and 2 flybys of Saturn revealed the presence of a variety of plasma waves associated with Saturn's magnetosphere, some electrostatic in nature, others apparently electromagnetic. Possibly the most unambiguous identification of the latter in the low-frequency range (less than 10 kHz) is of narrow-banded emissions observed over a 3-day period when Voyager 1 was outbound. Persistent bands of emission near 5 kHz were seen from 19 to 58 Rs (where Rs is Saturn's radius = 60,330 km), and as the plasma parameters varied widely along the trajectory over this range, it is difficult to envisage how these emissions could be anything but freely-propagating electromagnetic waves. Hitherto their source was unknown, but similar emissions have been observed within the magnetospheres of Jupiter and earth and, based on knowledge of the latter in particular, it is proposed here that the source of the Saturnian narrow-band emissions lies in electrostatic upper-hybrid waves near the equatorial plane just beyond the orbit of the moon Rhea.
On source radiation. [power output computation
NASA Technical Reports Server (NTRS)
Levine, H.
1980-01-01
The power output from given sources is usually ascertained via an energy flux integral over the normal directions to a remote (farfield) surface; an alternative procedure, which utilizes an integral that specifies the direct rate of working by the source on the resultant field, is described and illustrated for both point and continuous source distributions. A comparison between the respective procedures is made in the analysis of sound radiated from a periodic dipole source whose axis rotates in a plane, on a full or partial angular range, with prescribed frequency. Thus, adopting a conventional approach, Sretenskii (1956) characterizes the rotating dipole in terms of an infinite number of stationary ones along a pair of orthogonal directions in the plane and, through the farfield representation of the latter, arrives at a series development for the instantaneous radiated power, whereas the local manner of power calculation dispenses with the equivalent infinite aggregate of sources and yields a compact analytical result.
Potential and Flux Field Landscape Theory of Spatially Inhomogeneous Non-Equilibrium Systems
NASA Astrophysics Data System (ADS)
Wu, Wei
In this dissertation we establish a potential and flux field landscape theory for studying the global stability and dynamics as well as the non-equilibrium thermodynamics of spatially inhomogeneous non-equilibrium dynamical systems. The potential and flux landscape theory developed previously for spatially homogeneous non-equilibrium stochastic systems described by Langevin and Fokker-Planck equations is refined and further extended to spatially inhomogeneous non-equilibrium stochastic systems described by functional Langevin and Fokker-Planck equations. The probability flux field is found to be crucial in breaking detailed balance and characterizing non-equilibrium effects of spatially inhomogeneous systems. It also plays a pivotal role in governing the global dynamics and formulating a set of non-equilibrium thermodynamic equations for a generic class of spatially inhomogeneous stochastic systems. The general formalism is illustrated by studying more specific systems and processes, such as the reaction diffusion system, the Ornstein-Uhlenbeck process, the Brusselator reaction diffusion model, and the spatial stochastic neuronal model. The theory can be applied to a variety of physical, chemical and biological spatially inhomogeneous non-equilibrium systems abundant in nature.
Jovian S emission: Model of radiation source
NASA Astrophysics Data System (ADS)
Ryabov, B. P.
1994-04-01
A physical model of the radiation source and an excitation mechanism have been suggested for the S component in Jupiter's sporadic radio emission. The model provides a unique explanation for most of the interrelated phenomena observed, allowing a consistent interpretation of the emission cone structure, behavior of the integrated radio spectrum, occurrence probability of S bursts, location and size of the radiation source, and fine structure of the dynamic spectra. The mechanism responsible for the S bursts is also discussed in connection with the L type emission. Relations are traced between parameters of the radio emission and geometry of the Io flux tube. Fluctuations in the current amplitude through the tube are estimated, along with the refractive index value and mass density of the plasma near the radiation source.
Sources and measurement of ultraviolet radiation.
Diffey, Brian L
2002-09-01
Ultraviolet (UV) radiation is part of the electromagnetic spectrum. The biological effects of UV radiation vary enormously with wavelength and for this reason the UV spectrum is further subdivided into three regions: UVA, UVB, and UVC. Quantities of UV radiation are expressed using radiometric terminology. A particularly important term in clinical photobiology is the standard erythema dose (SED), which is a measure of the erythemal effectiveness of a UV exposure. UV radiation is produced either by heating a body to an incandescent temperature, as is the case with solar UV, or by passing an electric current through a gas, usually vaporized mercury. The latter process is the mechanism whereby UV radiation is produced artificially. Both the quality (spectrum) and quantity (intensity) of terrestrial UV radiation vary with factors including the elevation of the sun above the horizon and absorption and scattering by molecules in the atmosphere, notably ozone, and by clouds. For many experimental studies in photobiology it is simply not practicable to use natural sunlight and so artificial sources of UV radiation designed to simulate the UV component of sunlight are employed; these are based on either optically filtered xenon arc lamps or fluorescent lamps. The complete way to characterize an UV source is by spectroradiometry, although for most practical purposes a detector optically filtered to respond to a limited portion of the UV spectrum normally suffices.
Sources and measurement of ultraviolet radiation.
Diffey, Brian L
2002-09-01
Ultraviolet (UV) radiation is part of the electromagnetic spectrum. The biological effects of UV radiation vary enormously with wavelength and for this reason the UV spectrum is further subdivided into three regions: UVA, UVB, and UVC. Quantities of UV radiation are expressed using radiometric terminology. A particularly important term in clinical photobiology is the standard erythema dose (SED), which is a measure of the erythemal effectiveness of a UV exposure. UV radiation is produced either by heating a body to an incandescent temperature, as is the case with solar UV, or by passing an electric current through a gas, usually vaporized mercury. The latter process is the mechanism whereby UV radiation is produced artificially. Both the quality (spectrum) and quantity (intensity) of terrestrial UV radiation vary with factors including the elevation of the sun above the horizon and absorption and scattering by molecules in the atmosphere, notably ozone, and by clouds. For many experimental studies in photobiology it is simply not practicable to use natural sunlight and so artificial sources of UV radiation designed to simulate the UV component of sunlight are employed; these are based on either optically filtered xenon arc lamps or fluorescent lamps. The complete way to characterize an UV source is by spectroradiometry, although for most practical purposes a detector optically filtered to respond to a limited portion of the UV spectrum normally suffices. PMID:12231182
Sources of Coherent Terahertz Radiation
NASA Astrophysics Data System (ADS)
Bratman, Vladimir L.; Bandurkin, Ilya V.; Dumesh, Boris S.; Fedotov, Alexei E.; Kalynov, Yury K.; Kolganov, Nikolay G.; Manuilov, Vladimir N.; Rusin, Fedor S.; Samsonov, Sergey V.; Savilov, Andrey V.
2006-01-01
New results in the field of high-frequency gyrotrons, gyro-multipliers and orotrons allow one to consider these electron devices as promising candidates for the realization of powerful and available sources in Terahertz range. Electron beams with a very high compression of up to a factor of 4,400 have been obtained and selective generation at the 1st-5th cyclotron harmonics have been demonstrated in Large Orbit Gyrotrons (LOGs) at millimeter and submillimeter wavelengths at operating voltages from 50 to 250 kV. When operating at the third cyclotron harmonic (TE3,8 and TE3,9 modes in the first oscillator; TE3,5 mode in the second oscillator) output power levels of 10-20 kW have been obtained in the frequency range of 0.37-0.41 THz. Gyro-multipliers with self-exciting low-frequency sections are proposed and studied theoretically. Low-voltage orotrons have been demonstrated in the frequency range of 0.1-0.4 THz with output powers of 1.0-0.1 W and typical electrical-mechanical frequency tunability within an octave range. Using the same voltage, orotrons can achieve higher power and frequency stability within the entire Terahertz range compared with BWOs that are the most widespread devices at these frequencies.
Sustainably Sourced, Thermally Resistant, Radiation Hard Biopolymer
NASA Technical Reports Server (NTRS)
Pugel, Diane
2011-01-01
This material represents a breakthrough in the production, manufacturing, and application of thermal protection system (TPS) materials and radiation shielding, as this represents the first effort to develop a non-metallic, non-ceramic, biomaterial-based, sustainable TPS with the capability to also act as radiation shielding. Until now, the standing philosophy for radiation shielding involved carrying the shielding at liftoff or utilizing onboard water sources. This shielding material could be grown onboard and applied as needed prior to different radiation landscapes (commonly seen during missions involving gravitational assists). The material is a bioplastic material. Bioplastics are any combination of a biopolymer and a plasticizer. In this case, the biopolymer is a starch-based material and a commonly accessible plasticizer. Starch molecules are composed of two major polymers: amylase and amylopectin. The biopolymer phenolic compounds are common to the ablative thermal protection system family of materials. With similar constituents come similar chemical ablation processes, with the potential to have comparable, if not better, ablation characteristics. It can also be used as a flame-resistant barrier for commercial applications in buildings, homes, cars, and heater firewall material. The biopolymer is observed to undergo chemical transformations (oxidative and structural degradation) at radiation doses that are 1,000 times the maximum dose of an unmanned mission (10-25 Mrad), indicating that it would be a viable candidate for robust radiation shielding. As a comparison, the total integrated radiation dose for a three-year manned mission to Mars is 0.1 krad, far below the radiation limit at which starch molecules degrade. For electron radiation, the biopolymer starches show minimal deterioration when exposed to energies greater than 180 keV. This flame-resistant, thermal-insulating material is non-hazardous and may be sustainably sourced. It poses no hazardous
Dynamic relaxation of a levitated nanoparticle from a non-equilibrium steady state.
Gieseler, Jan; Quidant, Romain; Dellago, Christoph; Novotny, Lukas
2014-05-01
Fluctuation theorems are a generalization of thermodynamics on small scales and provide the tools to characterize the fluctuations of thermodynamic quantities in non-equilibrium nanoscale systems. They are particularly important for understanding irreversibility and the second law in fundamental chemical and biological processes that are actively driven, thus operating far from thermal equilibrium. Here, we apply the framework of fluctuation theorems to investigate the important case of a system relaxing from a non-equilibrium state towards equilibrium. Using a vacuum-trapped nanoparticle, we demonstrate experimentally the validity of a fluctuation theorem for the relative entropy change occurring during relaxation from a non-equilibrium steady state. The platform established here allows non-equilibrium fluctuation theorems to be studied experimentally for arbitrary steady states and can be extended to investigate quantum fluctuation theorems as well as systems that do not obey detailed balance.
Radiation safety of sealed radioactive sources.
Pryor, Kathryn H
2015-02-01
Sealed radioactive sources are used in a wide variety of occupational settings and under differing regulatory/licensing structures. The definition of a sealed radioactive source varies between U.S. regulatory authorities and standard-setting organizations. Potential problems with sealed sources cover a range of risks and impacts. The loss of control of high activity sealed sources can result in very high or even fatal doses to members of the public who come in contact with them. Sources that are not adequately sealed and that fail can cause spread of contamination and potential intake of radioactive material. There is also the possibility that sealed sources may be (or threaten to be) used for terrorist purposes and disruptive opportunities. Until fairly recently, generally licensed sealed sources and devices received little, if any, regulatory oversight and were often forgotten, lost or unaccounted for. Nonetheless, generally licensed devices can contain fairly significant quantities of radioactive material, and there is some potential for exposure if a device is treated in a way for which it was never designed. Industrial radiographers use and handle high activity and/or high dose-rate sealed sources in the field with a high degree of independence and minimal regulatory oversight. Failure to follow operational procedures and properly handle radiography sources can and has resulted in serious injuries and death. Industrial radiographers have experienced a disproportionately large fraction of incidents that have resulted in unintended exposure to radiation. Sources do not have to contain significant quantities of radioactive material to cause problems in the event of their failure. A loss of integrity can cause the spread of contamination and potential exposure to workers and members of the public. The National Council on Radiation Protection and Measurements has previously provided recommendations on select aspects of sealed source programs. Future efforts to
Synthesis of Silane and Silicon in a Non-equilibrium Plasma Jet
NASA Technical Reports Server (NTRS)
Calcote, H. F.
1978-01-01
The original objective of this program was to determine the feasibility of high volume, low-cost production of high purity silane or solar cell grade silicon using a non equilibrium plasma jet. The emphasis was changed near the end of the program to determine the feasibility of preparing photovoltaic amorphous silicon films directly using this method. The non equilibrium plasma jet should be further evaluated as a technique for producing high efficiency photovoltaic amorphous silicon films.
Non-equilibrium Steady States in Kac's Model Coupled to a Thermostat
NASA Astrophysics Data System (ADS)
Evans, Josephine
2016-09-01
This paper studies the existence, uniqueness and convergence to non-equilibrium steady states in Kac's model with an external coupling. We work in both Fourier distances and Wasserstein distances. Our methods work in the case where the external coupling is not a Maxwellian equilibrium. This provides an example of a non-equilibrium steady state. We also study the behaviour as the number of particles goes to infinity and show quantitative estimates on the convergence rate of the first marginal.
Star formation and molecular hydrogen in dwarf galaxies: a non-equilibrium view
NASA Astrophysics Data System (ADS)
Hu, Chia-Yu; Naab, Thorsten; Walch, Stefanie; Glover, Simon C. O.; Clark, Paul C.
2016-06-01
We study the connection of star formation to atomic (H I) and molecular hydrogen (H2) in isolated, low-metallicity dwarf galaxies with high-resolution (mgas = 4 M⊙, Nngb = 100) smoothed particle hydrodynamics simulations. The model includes self-gravity, non-equilibrium cooling, shielding from a uniform and constant interstellar radiation field, the chemistry of H2 formation, H2-independent star formation, supernova feedback and metal enrichment. We find that the H2 mass fraction is sensitive to the adopted dust-to-gas ratio and the strength of the interstellar radiation field, while the star formation rate is not. Star formation is regulated by stellar feedback, keeping the gas out of thermal equilibrium for densities n < 1 cm-3. Because of the long chemical time-scales, the H2 mass remains out of chemical equilibrium throughout the simulation. Star formation is well correlated with cold (T ≤ 100 K) gas, but this dense and cold gas - the reservoir for star formation - is dominated by H I, not H2. In addition, a significant fraction of H2 resides in a diffuse, warm phase, which is not star-forming. The interstellar medium is dominated by warm gas (100 K < T ≤ 3 × 104 K) both in mass and in volume. The scaleheight of the gaseous disc increases with radius while the cold gas is always confined to a thin layer in the mid-plane. The cold gas fraction is regulated by feedback at small radii and by the assumed radiation field at large radii. The decreasing cold gas fractions result in a rapid increase in depletion time (up to 100 Gyr) for total gas surface densities Σ _{H I+H_2} ≲ 10 M⊙ pc-2, in agreement with observations of dwarf galaxies in the Kennicutt-Schmidt plane.
NASA Astrophysics Data System (ADS)
Glowacki, David R.; Lightfoot, Robert; Harvey, Jeremy N.
2013-03-01
The ability to characterise and control matter far away from equilibrium is a frontier challenge facing modern science. In this article, we sketch out a heuristic structure for thinking about the different ways in which non-equilibrium phenomena can impact molecular reaction dynamics. Our analytical schema includes three different regimes, organised according to increasing dynamical resolution: at the lowest resolution, we have conformer phase space, at an intermediate resolution, we have energy space; and at the highest resolution, we have mode space. Within each regime, we discuss practical definitions of non-equilibrium phenomena, mostly in terms of the corresponding relaxation timescales. Using this analytical framework, we discuss some recent non-equilibrium reaction dynamics studies spanning isolated small-molecule ensembles, gas-phase ensembles and solution-phase ensembles. This includes new results that provide insight into how non-equilibrium phenomena impact the solution-phase alkene-hydroboration reaction. We emphasise that interesting non-equilibrium dynamical phenomena often occur when the relaxation timescales characterising each regime are similar. In closing, we reflect on outstanding challenges and future research directions to guide our understanding of how non-equilibrium phenomena impact reaction dynamics.
Gravitational energy, local holography and non-equilibrium thermodynamics
NASA Astrophysics Data System (ADS)
Freidel, Laurent
2015-03-01
We study the properties of gravitational systems in finite regions bounded by gravitational screens. We present a detailed construction of the total energy of such regions and of the energy and momentum balance equations due to the flow of matter and gravitational radiation through the screen. We establish that the gravitational screen possesses analogs of surface tension, internal energy, and viscous stress tensor, while the conservations are analogs of nonequilibrium balance equations for a viscous system. This gives a precise correspondence between gravity in finite regions and nonequilibrium thermodynamics.
Radiation Safety of Sealed Radioactive Sources
Pryor, Kathryn H.
2015-01-29
Sealed radioactive sources are used in a wide variety of occupational settings and under differing regulatory/licensing structures. The definition of a sealed radioactive source varies between US regulatory authorities and standard-setting organizations. Potential problems with sealed sources cover a range of risks and impacts. The loss of control of high activity sealed sources can result in very high or even fatal doses to members of the public who come in contact with them. Sources that are not adequately sealed, and that fail, can cause spread of contamination and potential intake of radioactive material. There is also the possibility that sealed sources may be (or threatened to be) used for terrorist purposes and disruptive opportunities. Until fairly recently, generally-licensed sealed sources and devices received little, if any, regulatory oversight, and were often forgotten, lost or unaccounted for. Nonetheless, generally licensed devices can contain fairly significant quantities of radioactive material and there is some potential for exposure if a device is treated in a way that it was never designed. Industrial radiographers use and handle high activity and/or high-dose rate sealed sources in the field with a high degree of independence and minimal regulatory oversight. Failure to follow operational procedures and properly handle radiography sources can and has resulted in serious injuries and death. Industrial radiographers have experienced a disproportionately large fraction of incidents that result in unintended exposure to radiation. Sources do not have to contain significant quantities of radioactive material to cause problems in the event of their failure. A loss of integrity can cause the spread of contamination and potential exposure to workers and members of the public. The NCRP has previously provided recommendations on select aspects of sealed source programs. Future efforts to provide recommendations for sealed source programs are discussed.
Plasma wake field XUV radiation source
Prono, Daniel S.; Jones, Michael E.
1997-01-01
A XUV radiation source uses an interaction of electron beam pulses with a gas to create a plasma radiator. A flowing gas system (10) defines a circulation loop (12) with a device (14), such as a high pressure pump or the like, for circulating the gas. A nozzle or jet (16) produces a sonic atmospheric pressure flow and increases the density of the gas for interacting with an electron beam. An electron beam is formed by a conventional radio frequency (rf) accelerator (26) and electron pulses are conventionally formed by a beam buncher (28). The rf energy is thus converted to electron beam energy, the beam energy is used to create and then thermalize an atmospheric density flowing gas to a fully ionized plasma by interaction of beam pulses with the plasma wake field, and the energetic plasma then loses energy by line radiation at XUV wavelengths Collection and focusing optics (18) are used to collect XUV radiation emitted as line radiation when the high energy density plasma loses energy that was transferred from the electron beam pulses to the plasma.
Non-equilibrium STLS approach to transport properties of single impurity Anderson model
NASA Astrophysics Data System (ADS)
Rezai, Raheleh; Ebrahimi, Farshad
2014-04-01
In this work, using the non-equilibrium Keldysh formalism, we study the effects of the electron-electron interaction and the electron-spin correlation on the non-equilibrium Kondo effect and the transport properties of the symmetric single impurity Anderson model (SIAM) at zero temperature by generalizing the self-consistent method of Singwi, Tosi, Land, and Sjolander (STLS) for a single-band tight-binding model with Hubbard type interaction to out of equilibrium steady-states. We at first determine in a self-consistent manner the non-equilibrium spin correlation function, the effective Hubbard interaction, and the double-occupancy at the impurity site. Then, using the non-equilibrium STLS spin polarization function in the non-equilibrium formalism of the iterative perturbation theory (IPT) of Yosida and Yamada, and Horvatic and Zlatic, we compute the spectral density, the current-voltage characteristics and the differential conductance as functions of the applied bias and the strength of on-site Hubbard interaction. We compare our spectral densities at zero bias with the results of numerical renormalization group (NRG) and depict the effects of the electron-electron interaction and electron-spin correlation at the impurity site on the aforementioned properties by comparing our numerical result with the order U2 IPT. Finally, we show that the obtained numerical results on the differential conductance have a quadratic universal scaling behavior and the resulting Kondo temperature shows an exponential behavior.
Black silicon-based infrared radiation source
NASA Astrophysics Data System (ADS)
Anwar, Momen; Sabry, Yasser; Basset, Philippe; Marty, Frédéric; Bourouina, Tarik; Khalil, Diaa
2016-03-01
Micromachined infrared sources are enabling component for interferometric and spectroscopic sensors. Their compact size and low cost transform bulky instruments to the sensor scale, which is needed for a wide range of applications in the conventional and unconventional environments. The silicon micromachined sources should be engineered to have good emissivity across a large wavelength range because the intrinsic emissivity of silicon is low. This optimization was reported in literature by either the deposition of black metal at the surface of an emitter or the use of deep phonic crystal cavities, which complicates the fabrication technology and results in sharp dip lines in the spectral emissivity, respectively. In this work we report a micromachined infrared radiation source based on a heater on the top of black silicon structure for the first time in the literature, up to the authors' knowledge. The temperature of the device is characterized versus the applied voltage and the radiated spectrum is captured in the 1300 nm to 2500 nm spectral range; limited by the spectrum analysis instrument. The reported source opens the doors for completely integrated MEMS spectral sensors onchip.
Stout, R B
2001-04-01
A theoretical expression is developed for the dissolution rate response for multi-component radioactive materials that have surface adsorption kinetics and radiolysis kinetics when wetted by a multi-component aqueous solution. An application for this type of dissolution response is the performance evaluation of multi-component spent nuclear fuels (SNFs) for long term interim storage and for geological disposition. Typically, SNF compositions depend on initial composition, uranium oxide and metal alloys being most common, and on reactor burnup which results in a wide range of fission product and actinide concentrations that decay by alpha, beta, and gamma radiation. These compositional/burnup ranges of SNFs, whether placed in interim storage or emplaced in a geologic repository, will potentially be wetted by multi-component aqueous solutions, and these solutions may be further altered by radiolytic aqueous species due to three radiation fields. The solid states of the SNFs are not thermodynamically stable when wetted and will dissolve, with or without radiolysis. The following development of a dissolution theory is based on a non-equilibrium thermodynamic analysis of energy reactions and energy transport across a solid-liquid phase change discontinuity that propagates at a quasi-steady, dissolution velocity. The integral form of the energy balance equation is used for this spatial surface discontinuity analysis. The integral formulation contains internal energy functional of classical thermodynamics for both the SNFs' solid state and surface adsorption species, and the adjacent liquid state, which includes radiolytic chemical species. The steady-state concentrations of radiolytic chemical species are expressed by an approximate analysis of the decay radiation transport equation. For purposes of illustration a modified Temkin adsorption isotherm was assumed for the surface adsorption kinetics on an arbitrary, finite area of the solid-liquid dissolution interface. For
Non-equilibrium effects upon the non-Markovian Caldeira-Leggett quantum master equation
Bolivar, A.O.
2011-05-15
Highlights: > Classical Brownian motion described by a non-Markovian Fokker-Planck equation. > Quantization process. > Quantum Brownian motion described by a non-Markovian Caldeira-Leggett equation. > A non-equilibrium quantum thermal force is predicted. - Abstract: We obtain a non-Markovian quantum master equation directly from the quantization of a non-Markovian Fokker-Planck equation describing the Brownian motion of a particle immersed in a generic environment (e.g. a non-thermal fluid). As far as the especial case of a heat bath comprising of quantum harmonic oscillators is concerned, we derive a non-Markovian Caldeira-Leggett master equation on the basis of which we work out the concept of non-equilibrium quantum thermal force exerted by the harmonic heat bath upon the Brownian motion of a free particle. The classical limit (or dequantization process) of this sort of non-equilibrium quantum effect is scrutinized, as well.
The non-equilibrium phase diagrams of flow-induced crystallization and melting of polyethylene.
Wang, Zhen; Ju, Jianzhu; Yang, Junsheng; Ma, Zhe; Liu, Dong; Cui, Kunpeng; Yang, Haoran; Chang, Jiarui; Huang, Ningdong; Li, Liangbin
2016-09-09
Combining extensional rheology with in-situ synchrotron ultrafast x-ray scattering, we studied flow-induced phase behaviors of polyethylene (PE) in a wide temperature range up to 240 °C. Non-equilibrium phase diagrams of crystallization and melting under flow conditions are constructed in stress-temperature space, composing of melt, non-crystalline δ, hexagonal and orthorhombic phases. The non-crystalline δ phase is demonstrated to be either a metastable transient pre-order for crystallization or a thermodynamically stable phase. Based on the non-equilibrium phase diagrams, nearly all observations in flow-induced crystallization (FIC) of PE can be well understood. The interplay of thermodynamic stabilities and kinetic competitions of the four phases creates rich kinetic pathways for FIC and diverse final structures. The non-equilibrium flow phase diagrams provide a detailed roadmap for precisely processing of PE with designed structures and properties.
The non-equilibrium phase diagrams of flow-induced crystallization and melting of polyethylene
Wang, Zhen; Ju, Jianzhu; Yang, Junsheng; Ma, Zhe; Liu, Dong; Cui, Kunpeng; Yang, Haoran; Chang, Jiarui; Huang, Ningdong; Li, Liangbin
2016-01-01
Combining extensional rheology with in-situ synchrotron ultrafast x-ray scattering, we studied flow-induced phase behaviors of polyethylene (PE) in a wide temperature range up to 240 °C. Non-equilibrium phase diagrams of crystallization and melting under flow conditions are constructed in stress-temperature space, composing of melt, non-crystalline δ, hexagonal and orthorhombic phases. The non-crystalline δ phase is demonstrated to be either a metastable transient pre-order for crystallization or a thermodynamically stable phase. Based on the non-equilibrium phase diagrams, nearly all observations in flow-induced crystallization (FIC) of PE can be well understood. The interplay of thermodynamic stabilities and kinetic competitions of the four phases creates rich kinetic pathways for FIC and diverse final structures. The non-equilibrium flow phase diagrams provide a detailed roadmap for precisely processing of PE with designed structures and properties. PMID:27609305
The non-equilibrium phase diagrams of flow-induced crystallization and melting of polyethylene.
Wang, Zhen; Ju, Jianzhu; Yang, Junsheng; Ma, Zhe; Liu, Dong; Cui, Kunpeng; Yang, Haoran; Chang, Jiarui; Huang, Ningdong; Li, Liangbin
2016-01-01
Combining extensional rheology with in-situ synchrotron ultrafast x-ray scattering, we studied flow-induced phase behaviors of polyethylene (PE) in a wide temperature range up to 240 °C. Non-equilibrium phase diagrams of crystallization and melting under flow conditions are constructed in stress-temperature space, composing of melt, non-crystalline δ, hexagonal and orthorhombic phases. The non-crystalline δ phase is demonstrated to be either a metastable transient pre-order for crystallization or a thermodynamically stable phase. Based on the non-equilibrium phase diagrams, nearly all observations in flow-induced crystallization (FIC) of PE can be well understood. The interplay of thermodynamic stabilities and kinetic competitions of the four phases creates rich kinetic pathways for FIC and diverse final structures. The non-equilibrium flow phase diagrams provide a detailed roadmap for precisely processing of PE with designed structures and properties. PMID:27609305
The non-equilibrium phase diagrams of flow-induced crystallization and melting of polyethylene
NASA Astrophysics Data System (ADS)
Wang, Zhen; Ju, Jianzhu; Yang, Junsheng; Ma, Zhe; Liu, Dong; Cui, Kunpeng; Yang, Haoran; Chang, Jiarui; Huang, Ningdong; Li, Liangbin
2016-09-01
Combining extensional rheology with in-situ synchrotron ultrafast x-ray scattering, we studied flow-induced phase behaviors of polyethylene (PE) in a wide temperature range up to 240 °C. Non-equilibrium phase diagrams of crystallization and melting under flow conditions are constructed in stress-temperature space, composing of melt, non-crystalline δ, hexagonal and orthorhombic phases. The non-crystalline δ phase is demonstrated to be either a metastable transient pre-order for crystallization or a thermodynamically stable phase. Based on the non-equilibrium phase diagrams, nearly all observations in flow-induced crystallization (FIC) of PE can be well understood. The interplay of thermodynamic stabilities and kinetic competitions of the four phases creates rich kinetic pathways for FIC and diverse final structures. The non-equilibrium flow phase diagrams provide a detailed roadmap for precisely processing of PE with designed structures and properties.
Steady-State Density Functional Theory for Non-equilibrium Quantum Systems
NASA Astrophysics Data System (ADS)
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.).
Network Algorithms for Detection of Radiation Sources
Rao, Nageswara S; Brooks, Richard R; Wu, Qishi
2014-01-01
In support of national defense, Domestic Nuclear Detection Office s (DNDO) Intelligent Radiation Sensor Systems (IRSS) program supported the development of networks of radiation counters for detecting, localizing and identifying low-level, hazardous radiation sources. Industry teams developed the first generation of such networks with tens of counters, and demonstrated several of their capabilities in indoor and outdoor characterization tests. Subsequently, these test measurements have been used in algorithm replays using various sub-networks of counters. Test measurements combined with algorithm outputs are used to extract Key Measurements and Benchmark (KMB) datasets. We present two selective analyses of these datasets: (a) a notional border monitoring scenario that highlights the benefits of a network of counters compared to individual detectors, and (b) new insights into the Sequential Probability Ratio Test (SPRT) detection method, which lead to its adaptations for improved detection. Using KMB datasets from an outdoor test, we construct a notional border monitoring scenario, wherein twelve 2 *2 NaI detectors are deployed on the periphery of 21*21meter square region. A Cs-137 (175 uCi) source is moved across this region, starting several meters from outside and finally moving away. The measurements from individual counters and the network were processed using replays of a particle filter algorithm developed under IRSS program. The algorithm outputs from KMB datasets clearly illustrate the benefits of combining measurements from all networked counters: the source was detected before it entered the region, during its trajectory inside, and until it moved several meters away. When individual counters are used for detection, the source was detected for much shorter durations, and sometimes was missed in the interior region. The application of SPRT for detecting radiation sources requires choosing the detection threshold, which in turn requires a source strength
Non-equilibrium Ionization Modeling of Simulated Pseudostreamers in a Solar Corona Model
NASA Astrophysics Data System (ADS)
Shen, Chengcai; Raymond, John C.; Mikić, Zoran; Linker, Jon; Reeves, Katharine K.; Murphy, Nicholas A.
2015-04-01
Time-dependent ionization is important for diagnostics of coronal streamers, where the thermodynamic time scale could be shorter than the ionization or recombination time scales, and ions are therefor in non-equilibrium ionization states. In this work, we perform post-processing time-dependent ionization calculations for a three dimensional solar corona and inner heliosphere model from Predictive Sciences Inc. (Mikić & Linker 1999) to analyze the influence of non-equilibrium ionization on emission from coronal streamers. Using the plasma temperature, density, velocity and magnetic field distributions provided by the 3D MHD simulation covering the Whole Sun Month (Carrington rotation CR1913, 1996 August 22 to September 18), we calculate non-equilibrium ionization states in the region around a pseudostreamer. We then obtain the synthetic emissivities with the non-equilibrium ion populations. Under the assumption that the corona is optically thin, we also obtain intensity profiles of several emission lines. We compare our calculations with intensities of Lyman-alpha lines and OVI lines from SOHO/Ultraviolet Coronagraph Spectrometer (UVCS) observations at 14 different heights. The results show that intensity profiles of both Lyman-alpha and OVI lines match well UVCS observations at low heights. At large heights, OVI intensites are higher for non-equilibrium ionization than equilibrium ionization inside this pseudostreamer. The assumption of ionization equilibrium would lead to a underestimate of the OVI intensity by about ten percent at a height of 2 solar radii, and the difference between these two ionization cases increases with height. The intensity ratio of OVI 1032 line to OVI 1037 lines is also obtained for non-equilibrium ionization modeling.
Helical Cerenkov effect, a novel radiation source
Soln, J. )
1994-10-01
The observability of the helical Cerenkov effect as a novel radiation source is discussed. Depending on the value of the index of refraction of the medium, the strength of the uniform magnetic field, and the electron beam energy, helical Cerenkov radiation can occur in the same spectral regions as the ordinary Cerenkov effect, that is, from microwave to visible wavelengths. From the kinematics point of view, the author argues that for a microwave wavelength of 10[sup [minus]1] cm this effect should be observable in a medium with an index of refraction of 1.4, with a beam energy of 3 MeV, and a uniform magnetic field of 4 T. On the specific level, however, for the sake of simplicity, he discusses the observability of this effect for visible light with the central wavelength of 5 [times] 10[sup [minus]5] cm which can be achieved with 2 MeV in beam energy, silica aerogel as a medium (with an index of refraction of 1.075), and uniform magnetic fields from 5 to 10 T. For a 10-T magnetic field, he calculates that in the visible region of 250 to 750 nm an electron will produce a photon per 10 cm of traveled length. As to the stimulated helical Cerenkov emission, the author estimates that respectable gains are possible even if the beam passes close to the dielectric rather than through it. In addition to being potentially a new radiation source, the helical Cerenkov effect could possibly be used as a detector of radiation by energetic electrons that are trapped in a medium by strong magnetic fields.
21 CFR 886.5100 - Ophthalmic beta radiation source.
Code of Federal Regulations, 2012 CFR
2012-04-01
... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Ophthalmic beta radiation source. 886.5100 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5100 Ophthalmic beta radiation source. (a) Identification. An ophthalmic beta radiation source is a device intended to apply...
21 CFR 886.5100 - Ophthalmic beta radiation source.
Code of Federal Regulations, 2014 CFR
2014-04-01
... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Ophthalmic beta radiation source. 886.5100 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5100 Ophthalmic beta radiation source. (a) Identification. An ophthalmic beta radiation source is a device intended to apply...
21 CFR 886.5100 - Ophthalmic beta radiation source.
Code of Federal Regulations, 2011 CFR
2011-04-01
... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ophthalmic beta radiation source. 886.5100 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5100 Ophthalmic beta radiation source. (a) Identification. An ophthalmic beta radiation source is a device intended to apply...
21 CFR 886.5100 - Ophthalmic beta radiation source.
Code of Federal Regulations, 2013 CFR
2013-04-01
... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Ophthalmic beta radiation source. 886.5100 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5100 Ophthalmic beta radiation source. (a) Identification. An ophthalmic beta radiation source is a device intended to apply...
21 CFR 886.5100 - Ophthalmic beta radiation source.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ophthalmic beta radiation source. 886.5100 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5100 Ophthalmic beta radiation source. (a) Identification. An ophthalmic beta radiation source is a device intended to apply...
Bresme, F.; Armstrong, J.
2014-01-07
We report non-equilibrium molecular dynamics simulations of heat transport in models of molecular fluids. We show that the “local” thermal conductivities obtained from non-equilibrium molecular dynamics simulations agree within numerical accuracy with equilibrium Green-Kubo computations. Our results support the local equilibrium hypothesis for transport properties. We show how to use the local dependence of the thermal gradients to quantify the thermal conductivity of molecular fluids for a wide range of thermodynamic states using a single simulation.
Non-equilibrium STLS approach to transport properties of single impurity Anderson model
Rezai, Raheleh Ebrahimi, Farshad
2014-04-15
In this work, using the non-equilibrium Keldysh formalism, we study the effects of the electron–electron interaction and the electron-spin correlation on the non-equilibrium Kondo effect and the transport properties of the symmetric single impurity Anderson model (SIAM) at zero temperature by generalizing the self-consistent method of Singwi, Tosi, Land, and Sjolander (STLS) for a single-band tight-binding model with Hubbard type interaction to out of equilibrium steady-states. We at first determine in a self-consistent manner the non-equilibrium spin correlation function, the effective Hubbard interaction, and the double-occupancy at the impurity site. Then, using the non-equilibrium STLS spin polarization function in the non-equilibrium formalism of the iterative perturbation theory (IPT) of Yosida and Yamada, and Horvatic and Zlatic, we compute the spectral density, the current–voltage characteristics and the differential conductance as functions of the applied bias and the strength of on-site Hubbard interaction. We compare our spectral densities at zero bias with the results of numerical renormalization group (NRG) and depict the effects of the electron–electron interaction and electron-spin correlation at the impurity site on the aforementioned properties by comparing our numerical result with the order U{sup 2} IPT. Finally, we show that the obtained numerical results on the differential conductance have a quadratic universal scaling behavior and the resulting Kondo temperature shows an exponential behavior. -- Highlights: •We introduce for the first time the non-equilibrium method of STLS for Hubbard type models. •We determine the transport properties of SIAM using the non-equilibrium STLS method. •We compare our results with order-U2 IPT and NRG. •We show that non-equilibrium STLS, contrary to the GW and self-consistent RPA, produces the two Hubbard peaks in DOS. •We show that the method keeps the universal scaling behavior and correct
Studying non-equilibrium many-body dynamics using one-dimensional Bose gases
Langen, Tim; Gring, Michael; Kuhnert, Maximilian; Rauer, Bernhard; Geiger, Remi; Mazets, Igor; Smith, David Adu; Schmiedmayer, Jörg; Kitagawa, Takuya; Demler, Eugene
2014-12-04
Non-equilibrium dynamics of isolated quantum many-body systems play an important role in many areas of physics. However, a general answer to the question of how these systems relax is still lacking. We experimentally study the dynamics of ultracold one-dimensional (1D) Bose gases. This reveals the existence of a quasi-steady prethermalized state which differs significantly from the thermal equilibrium of the system. Our results demonstrate that the dynamics of non-equilibrium quantum many-body systems is a far richer process than has been assumed in the past.
Non-Equilibrium Thermodynamic Chemistry and the Composition of the Atmosphere of Mars
NASA Technical Reports Server (NTRS)
Levine, J. S.; Summers, M. E.
2003-01-01
A high priority objective of the Mars Exploration Program is to Determine if life exists today (MEPAG Goal I, Objective A). The measurement of gases of biogenic origin may be an approach to detect the presence of microbial life on the surface or subsurface of Mars. Chemical thermodynamic calculations indicate that on both Earth and Mars, certain gases should exist in extremely low concentrations, if at all. Microbial metabolic activity is an important non-equilibrium chemistry process on Earth, and if microbial life exists on Mars, may be an important nonequilibrium chemistry process on Mars. The non-equilibrium chemistry of the atmosphere of Mars is discussed in this paper.
Chang, Zhengshi; Zhang, Guanjun; Jiang, Nan; Cao, Zexian
2014-03-14
Non-equilibrium atmospheric pressure plasma jet (APPJ) is a cold plasma source that promises various innovative applications. The influence of Penning effect on the formation, propagation, and other physical properties of the plasma bullets in APPJ remains a debatable topic. By using a 10 cm wide active electrode and a frequency of applied voltage down to 0.5 Hz, the Penning effect caused by preceding discharges can be excluded. It was found that the Penning effect originating in a preceding discharge helps build a conductive channel in the gas flow and provide seed electrons, thus the discharge can be maintained at a low voltage which in turn leads to a smaller propagation speed for the plasma bullet. Photographs from an intensified charge coupled device reveal that the annular structure of the plasma plume for He is irrelevant to the Penning ionization process arising from preceding discharges. By adding NH{sub 3} into Ar to introduce Penning effect, the originally filamentous discharge of Ar can display a rather extensive plasma plume in ambient as He. These results are helpful for the understanding of the behaviors of non-equilibrium APPJs generated under distinct conditions and for the design of plasma jet features, especially the spatial distribution and propagation speed, which are essential for application.
NASA Astrophysics Data System (ADS)
Parsey, Guy; Güçlü, Yaman; Verboncoeur, John; Christlieb, Andrew
2013-09-01
In the context of microwave-coupled plasmas, within atmospheric pressure nozzle geometries, we have developed a kinetic global model (KGM) framework designed for quick exploration of parameter space. Our final goal is understanding key reaction pathways within non-equilibrium plasma assisted combustion (PAC). In combination with a Boltzmann equation solver, kinetic plasma and gas-phase chemistry are solved with iterative feedback to match observed bulk conditions from experiments; using a parameterized non-equilibrium electron energy distribution function (EEDF) to define electron-impact processes. The KGM is first applied to argon and ``air'' systems as a means of assessing the soundness of made assumptions. The test with ``air'' greatly increases the complexity by incorporating a plethora of excited states (e.g. translational and vibrational excitations) and providing new reaction pathways. The KGM is then applied to plasma driven combustion mechanisms (e.g. H2 or CH4 with an oxidizer source) which drastically increases the range of reaction time-scales. As the reaction mechanisms become more complex, availability of data will begin to hinder model physicality, requiring analytical and/or empirical treatment of gaps in data to maintain completeness of the reaction mechanisms. Supported by AFOSR and an MSU SPG.
NASA Astrophysics Data System (ADS)
Oyanagi, H.; Tayagaki, T.; Tanaka, K.
2003-01-01
We describe non-equilibrium-state x-ray absorption spectroscopy focusing on local structure of photo-excited states trapped at low temperature. For this purpose, a novel Ge 100 pixel array detector with a packing density of 88% was developed. The local structure of photo-induced phase of Fe(II) spin crossover complex, [Fe(2-pic)3]Cl2EtOH (2-pic=2-aminomethyl pyridine), was investigated at low temperature (T <150 K). The use of pixel array detector and high-flux synchrotron x-ray source (multipole wiggler) successfully provided x-ray absorption spectra with high quality, in-situ, during the photo-excitation. It was found that the photo-induced phase under optical pumping at low temperature (T < 50 K) has an octahedral geometry with the elongated Fe-N distance (2.16 ± 0.01 Å), stabilizing the high spin state (S=2) configuration. No indication of symmetry breaking of FeN6 clusters upon LS↔HS spin-state switching was observed. It was demonstrated that the technique is a promising means to probe the local structure of non-equilibrium state such as trapped excited states or metastable states.
Comparison of photoexcited p-InAs THz radiation source with conventional thermal radiation sources
Smith, M. L.; Mendis, R.; Vickers, R. E. M.; Lewis, R. A.
2009-03-15
P-type InAs excited by ultrashort optical pulses has been shown to be a strong emitter of terahertz radiation. In a direct comparison between a p-InAs emitter and conventional thermal radiation sources, we demonstrate that under typical excitation conditions p-InAs produces more radiation below 1.2 THz than a globar. By treating the globar as a blackbody emitter we calibrate a silicon bolometer which is used to determine the power of the p-InAs emitter. The emitted terahertz power was found to be 98{+-}10 nW in this experiment.
NASA Astrophysics Data System (ADS)
Massman, W. J.
2015-11-01
Increased use of prescribed fire by land managers and the increasing likelihood of wildfires due to climate change require an improved modeling capability of extreme heating of soils during fires. This issue is addressed here by developing and testing the soil (heat-moisture-vapor) HMV-model, a 1-D (one-dimensional) non-equilibrium (liquid-vapor phase change) model of soil evaporation that simulates the coupled simultaneous transport of heat, soil moisture, and water vapor. This model is intended for use with surface forcing ranging from daily solar cycles to extreme conditions encountered during fires. It employs a linearized Crank-Nicolson scheme for the conservation equations of energy and mass and its performance is evaluated against dynamic soil temperature and moisture observations, which were obtained during laboratory experiments on soil samples exposed to surface heat fluxes ranging between 10 000 and 50 000 W m-2. The Hertz-Knudsen equation is the basis for constructing the model's non-equilibrium evaporative source term. Some unusual aspects of the model that were found to be extremely important to the model's performance include (1) a dynamic (temperature and moisture potential dependent) condensation coefficient associated with the evaporative source term, (2) an infrared radiation component to the soil's thermal conductivity, and (3) a dynamic residual soil moisture. This last term, which is parameterized as a function of temperature and soil water potential, is incorporated into the water retention curve and hydraulic conductivity functions in order to improve the model's ability to capture the evaporative dynamics of the strongly bound soil moisture, which requires temperatures well beyond 150 °C to fully evaporate. The model also includes film flow, although this phenomenon did not contribute much to the model's overall performance. In general, the model simulates the laboratory-observed temperature dynamics quite well, but is less precise (but
Non-linear optical diagnostic studies of high pressure non-equilibrium plasmas
NASA Astrophysics Data System (ADS)
Lempert, Walter
2012-10-01
Picosecond Coherent Anti-Stokes Raman Spectroscopy (CARS) is used for study of vibrational energy loading and relaxation kinetics in high pressure nitrogen and air nsec pulsed non-equilibrium plasmas in a pin-to-pin geometry. It is found that ˜33% of total discharge energy in a single pulse in air at 100 torr couples directly to nitrogen vibration by electron impact, in good agreement with master equation modeling predictions. However in the afterglow the total quanta in vibrational levels 0 -- 9 is found to increase by a factor of approximately 2 and 4 in nitrogen and air, respectively, a result in direct contrast to modeling results which predict the total number of quanta to be essentially constant. More detailed comparison between experiment and model show that the VDF predicted by the model during, and directly after, the discharge pulse is in good agreement with that determined experimentally, however for time delays exceeding ˜10 μsec the experimental and predicted VDFs diverge rapidly, particularly for levels v = 2 and greater. Specifically modeling predicts a rapid drop in population of high levels due to net downward V-V energy transfer whereas the experiment shows an increase in population in levels 2 and 3 and approximately constant population for higher levels. It is concluded that a collisional process is feeding high vibrational levels at a rate which is comparable to the rate at which population of the high levels is lost due to net downward V-V. A likely candidate for the source of additional vibrational quanta is the quenching of metastable electronic states of nitrogen to highly excited vibrational levels of the ground electronic state. Recent progress in the development and application of psec coherent Raman electric field and spontaneous Thomson scattering diagnostics for study of high pressure nsec pulsed plasmas will also be presented.
Technology Transfer Automated Retrieval System (TEKTRAN)
The distribution coefficient (KD) for the human drug carbamazepine was measured using a non-equilibrium technique. Repacked soil columns were prepared using an Airport silt loam (Typic Natrustalf) with an average organic matter content of 2.45%. Carbamazepine solutions were then leached through th...
A non-equilibrium potential function to study competition in neural systems
Mejias, Jorge F.
2011-03-24
In this work, I overview some novel results concerning the theoretical calculation of a non-equilibrium potential function for a biologically motivated model of a neural network. Such model displays competition between different populations of excitatory and inhibitory neurons, which is known to originate synchronous dynamics, fast activity oscillations, and other nontrivial behavior in more sophisticated models of neural media.
Non-equilibrium condensation process in holographic superconductor with nonlinear electrodynamics
NASA Astrophysics Data System (ADS)
Liu, Yunqi; Gong, Yungui; Wang, Bin
2016-02-01
We study the non-equilibrium condensation process in a holographic superconductor with nonlinear corrections to the U (1) gauge field. We start with an asymptotic Anti-de-Sitter (AdS) black hole against a complex scalar perturbation at the initial time, and solve the dynamics of the gravitational systems in the bulk. When the black hole temperature T is smaller than a critical value T c , the scalar perturbation grows exponentially till saturation, the final state of spacetime approaches to a hairy black hole. In the bulk theory, we find the clue of the influence of nonlinear corrections in the gauge filed on the process of the scalar field condensation. We show that the bulk dynamics in the non-equilibrium process is completely consistent with the observations on the boundary order parameter. Furthermore we examine the time evolution of horizons in the bulk non-equilibrium transformation process from the bald AdS black hole to the AdS hairy hole. Both the evolution of apparent and event horizons show that the original AdS black hole configuration requires more time to finish the transformation to become a hairy black hole if there is nonlinear correction to the electromagnetic field. We generalize our non-equilibrium discussions to the holographic entanglement entropy and find that the holographic entanglement entropy can give us further understanding of the influence of the nonlinearity in the gauge field on the scalar condensation.
A time-accurate implicit method for chemical non-equilibrium flows at all speeds
NASA Technical Reports Server (NTRS)
Shuen, Jian-Shun
1992-01-01
A new time accurate coupled solution procedure for solving the chemical non-equilibrium Navier-Stokes equations over a wide range of Mach numbers is described. The scheme is shown to be very efficient and robust for flows with velocities ranging from M less than or equal to 10(exp -10) to supersonic speeds.
NASA Astrophysics Data System (ADS)
Greenshields, Christopher J.; Reese, Jason M.
2012-07-01
This paper investigates the use of Navier-Stokes-Fourier equations with non-equilibrium boundary conditions (BCs) for simulation of rarefied hypersonic flows. It revisits a largely forgotten derivation of velocity slip and temperature jump by Patterson, based on Grad's moment method. Mach 10 flow around a cylinder and Mach 12.7 flow over a flat plate are simulated using both computational fluid dynamics using the temperature jump BCs of Patterson and Smoluchowski and the direct simulation Monte-Carlo (DSMC) method. These flows exhibit such strongly non-equilibrium behaviour that, following Patterson's analysis, they are strictly beyond the range of applicability of the BCs. Nevertheless, the results using Patterson's temperature jump BC compare quite well with the DSMC and are consistently better than those using the standard Smoluchowski temperature jump BC. One explanation for this better performance is that an assumption made by Patterson, based on the flow being only slightly non-equilibrium, introduces an additional constraint to the resulting BC model in the case of highly non-equilibrium flows.
A non-equilibrium potential function to study competition in neural systems
NASA Astrophysics Data System (ADS)
Mejías, Jorge F.
2011-03-01
In this work, I overview some novel results concerning the theoretical calculation of a non-equilibrium potential function for a biologically motivated model of a neural network. Such model displays competition between different populations of excitatory and inhibitory neurons, which is known to originate synchronous dynamics, fast activity oscillations, and other nontrivial behavior in more sophisticated models of neural media.
NASA Astrophysics Data System (ADS)
Bijie, Yang; Ning, Zhou; Quanhua, Sun
2016-01-01
The capacitively coupled plasma in the gaseous electronics conference reference reactor is numerically investigated for argon flow using a non-equilibrium plasma fluid model. The finite rate chemistry is adopted for the chemical non-equilibrium among species including neutral metastable, whereas a two-temperature model is employed to resolve the thermal non-equilibrium between electrons and heavy species. The predicted plasma density agrees very well with experimental data for the validation case. A strong thermal non-equilibrium is observed between heavy particles and electrons due to its low collision frequency, where the heavy species remains near ambient temperature for low pressure and low voltage conditions (0.1 Torr, 100 V). The effects of the operating parameters on the ion flux are also investigated, including the electrode voltage, chamber pressure, and gas flow rate. It is found that the ion flux can be increased by either elevating the electrode voltage or lowering the gas pressure. Project supported by the National Natural Science Foundation of China (Nos. 11372325, 11475239).
Rheology modulated non-equilibrium fluctuations in time-dependent diffusion processes
NASA Astrophysics Data System (ADS)
Maity, Debonil; Bandopadhyay, Aditya; Chakraborty, Suman
2016-11-01
The effect of non-Newtonian rheology, manifested through a viscoelastic linearized Maxwell model, on the time-dependent non-equilibrium concentration fluctuations due to free diffusion as well as thermal diffusion of a species is analyzed theoretically. Contrary to the belief that non-equilibrium Rayleigh line is not influenced by viscoelastic effects, through rigorous calculations, we put forward the fact that viscoelastic effects do influence the non-equilibrium Rayleigh line, while the effects are absent for the equilibrium scenario. The non-equilibrium process is quantified through the concentration fluctuation auto-correlation function, also known as the structure factor. The analysis reveals that the effect of rheology is prominent for both the cases of free diffusion and thermal diffusion at long times, where the influence of rheology dictates not only the location of the peaks in concentration dynamic structure factors, but also the magnitudes; such peaks in dynamic structure factors are absent in the case of Newtonian fluid. At smaller times, for the case of free diffusion, presence of time-dependent peak(s) are observed, which are weakly dependent on the influence of rheology, a phenomenon which is absent in the case of thermal diffusion. Different regimes of the frequency dependent overall dynamic structure factor, depending on the interplay of the fluid relaxation time and momentum diffusivity, are evaluated. The static structure factor is not affected to a great extent for the case of free-diffusion and is unaffected for the case of thermal diffusion.
Samarium-145 and its use as a radiation source
Fairchild, Ralph G.; Laster, Brenda H.; Packer, Samuel
1989-09-05
The present invention covers a new radiation source, samarium-145, with radiation energies slightly above those of I-125 and a half-life of 340 days. The samarium-145 source is produced by neutron irradiation of SM-144. This new source is useful as the implanted radiation source in photon activation therapy of malignant tumors to activate the stable I-127 contained in the IdUrd accumulated in the tumor, causing radiation sensitization and Auger cascades that irreperably damage the tumor cells. This new source is also useful as a brachytherapy source.
Samarium-145 and its use as a radiation source
Fairchild, Ralph G.; Laster, Brenda H.; Packer, Samuel
1989-01-01
The present invention covers a new radiation source, samarium-145, with radiation energies slightly above those of I-125 and a half-life of 340 days. The samarium-145 source is produced by neutron irradiation of SM-144. This new source is useful as the implanted radiation source in photon activation therapy of malignant tumors to activate the stable I-127 contained in the IdUrd accumulated in the tumor, causing radiation sensitization and Auger cascades that irreperably damage the tumor cells. This new source is also useful as a brachytherapy source.
Analysis of non-equilibrium phenomena in inductively coupled plasma generators
NASA Astrophysics Data System (ADS)
Zhang, W.; Lani, A.; Panesi, M.
2016-07-01
This work addresses the modeling of non-equilibrium phenomena in inductively coupled plasma discharges. In the proposed computational model, the electromagnetic induction equation is solved together with the set of Navier-Stokes equations in order to compute the electromagnetic and flow fields, accounting for their mutual interaction. Semi-classical statistical thermodynamics is used to determine the plasma thermodynamic properties, while transport properties are obtained from kinetic principles, with the method of Chapman and Enskog. Particle ambipolar diffusive fluxes are found by solving the Stefan-Maxwell equations with a simple iterative method. Two physico-mathematical formulations are used to model the chemical reaction processes: (1) A Local Thermodynamics Equilibrium (LTE) formulation and (2) a thermo-chemical non-equilibrium (TCNEQ) formulation. In the TCNEQ model, thermal non-equilibrium between the translational energy mode of the gas and the vibrational energy mode of individual molecules is accounted for. The electronic states of the chemical species are assumed in equilibrium with the vibrational temperature, whereas the rotational energy mode is assumed to be equilibrated with translation. Three different physical models are used to account for the coupling of chemistry and energy transfer processes. Numerical simulations obtained with the LTE and TCNEQ formulations are used to characterize the extent of non-equilibrium of the flow inside the Plasmatron facility at the von Karman Institute. Each model was tested using different kinetic mechanisms to assess the sensitivity of the results to variations in the reaction parameters. A comparison of temperatures and composition profiles at the outlet of the torch demonstrates that the flow is in non-equilibrium for operating conditions characterized by pressures below 30 000 Pa, frequency 0.37 MHz, input power 80 kW, and mass flow 8 g/s.
Radiative feedback and cosmic molecular gas: the role of different radiative sources
NASA Astrophysics Data System (ADS)
Maio, Umberto; Petkova, Margarita; De Lucia, Gabriella; Borgani, Stefano
2016-08-01
We present results from multifrequency radiative hydrodynamical chemistry simulations addressing primordial star formation and related stellar feedback from various populations of stars, stellar spectral energy distributions (SEDs) and initial mass functions. Spectra for massive stars, intermediate-mass stars and regular solar-like stars are adopted over a grid of 150 frequency bins and consistently coupled with hydrodynamics, heavy-element pollution and non-equilibrium species calculations. Powerful massive Population III stars are found to be able to largely ionize H and, subsequently, He and He+, causing an inversion of the equation of state and a boost of the Jeans masses in the early intergalactic medium. Radiative effects on star formation rates are between a factor of a few and 1 dex, depending on the SED. Radiative processes are responsible for gas heating and photoevaporation, although emission from soft SEDs has minor impacts. These findings have implications for cosmic gas preheating, primordial direct-collapse black holes, the build-up of `cosmic fossils' such as low-mass dwarf galaxies, the role of active galactic nuclei during reionization, the early formation of extended discs and angular-momentum catastrophe.
NASA Technical Reports Server (NTRS)
Yeh, Leehwa
1993-01-01
The phase-space-picture approach to quantum non-equilibrium statistical mechanics via the characteristic function of infinite-mode squeezed coherent states is introduced. We use quantum Brownian motion as an example to show how this approach provides an interesting geometrical interpretation of quantum non-equilibrium phenomena.
Intermittent Astrophysical Radiation Sources and Terrestrial Life
NASA Astrophysics Data System (ADS)
Melott, Adrian
2013-04-01
Terrestrial life is exposed to a variety of radiation sources. Astrophysical observations suggest that strong excursions in cosmic ray flux and spectral hardness are expected. Gamma-ray bursts and supernovae are expected to irradiate the atmosphere with keV to GeV photons at irregular intervals. Supernovae will produce large cosmic ray excursions, with time development varying with distance from the event. Large fluxes of keV to MeV protons from the Sun pose a strong threat to electromagnetic technology. The terrestrial record shows cosmogenic isotope excursions which are consistent with major solar proton events, and there are observations of G-stars suggesting that the rate of such events may be much higher than previously assumed. In addition there are unknown and unexplained astronomical transients which may indicate new classes of events. The Sun, supernovae, and gamma-ray bursts are all capable of producing lethal fluences, and some are expected on intervals of 10^8 years or so. The history of life on Earth is filled with mass extinctions at a variety of levels of intensity. Most are not understood. Astrophysical radiation may play a role, particularly from large increases in muon irradiation on the ground, and changes in atmospheric chemistry which deplete ozone, admitting increased solar UVB. UVB is strongly absorbed by DNA and proteins, and breaks the chemical bonds---it is a known carcinogen. High muon fluxes will also be damaging to such molecules, but experiments are needed to pin down the rate. Solar proton events which are not directly dangerous for the biota may nevertheless pose a major threat to modern electromagnetic technology through direct impact on satellites and magnetic induction of large currents in power grids, disabling transformers. We will look at the kind of events that are expected on timescales from human to geological, and their likely consequences.
Temperature Anisotropies of Thermal Non-equilibrium Ions by a Nonresonant AlfvÉn Wave
NASA Astrophysics Data System (ADS)
Liu, Hai-Feng; Tang, Chang-Jian; Wang, Xian-Qu; Zhang, Xin; Zhao, Yong
2016-09-01
From a significant view, considering the thermal non-equilibrium factor, we investigate Kappa (κ) ion temperature anisotropies induced by a low-frequency parallel propagating Alfvén wave by combining quasi-linear theory and test particle simulation. Analytic expressions for the ion temperature ratios {T}\\perp i/{T}//i and {T}\\perp i/{T}\\perp j are derived for the solar wind, where {T}\\perp i,{T}//i and {T}\\perp j denote the perpendicular temperature of species i, parallel temperature of species i, and perpendicular temperature of species j, respectively. The results of our model are broadly consistent, compared to observations of solar-wind measurements. Solar wind helium that meets the condition for strong core heating is nearly seven times hotter than hydrogen, on average. Furthermore, we note that we are able to predict the temperature anisotropies of ions based on their thermal non-equilibrium factors.
Non-equilibrium behaviour in coacervate-based protocells under electric-field-induced excitation
NASA Astrophysics Data System (ADS)
Yin, Yudan; Niu, Lin; Zhu, Xiaocui; Zhao, Meiping; Zhang, Zexin; Mann, Stephen; Liang, Dehai
2016-02-01
Although numerous strategies are now available to generate rudimentary forms of synthetic cell-like entities, minimal progress has been made in the sustained excitation of artificial protocells under non-equilibrium conditions. Here we demonstrate that the electric field energization of coacervate microdroplets comprising polylysine and short single strands of DNA generates membrane-free protocells with complex, dynamical behaviours. By confining the droplets within a microfluidic channel and applying a range of electric field strengths, we produce protocells that exhibit repetitive cycles of vacuolarization, dynamical fluctuations in size and shape, chaotic growth and fusion, spontaneous ejection and sequestration of matter, directional capture of solute molecules, and pulsed enhancement of enzyme cascade reactions. Our results highlight new opportunities for the study of non-equilibrium phenomena in synthetic protocells, provide a strategy for inducing complex behaviour in electrostatically assembled soft matter microsystems and illustrate how dynamical properties can be activated and sustained in microcompartmentalized media.
Non-equilibrium behaviour in coacervate-based protocells under electric-field-induced excitation
Yin, Yudan; Niu, Lin; Zhu, Xiaocui; Zhao, Meiping; Zhang, Zexin; Mann, Stephen; Liang, Dehai
2016-01-01
Although numerous strategies are now available to generate rudimentary forms of synthetic cell-like entities, minimal progress has been made in the sustained excitation of artificial protocells under non-equilibrium conditions. Here we demonstrate that the electric field energization of coacervate microdroplets comprising polylysine and short single strands of DNA generates membrane-free protocells with complex, dynamical behaviours. By confining the droplets within a microfluidic channel and applying a range of electric field strengths, we produce protocells that exhibit repetitive cycles of vacuolarization, dynamical fluctuations in size and shape, chaotic growth and fusion, spontaneous ejection and sequestration of matter, directional capture of solute molecules, and pulsed enhancement of enzyme cascade reactions. Our results highlight new opportunities for the study of non-equilibrium phenomena in synthetic protocells, provide a strategy for inducing complex behaviour in electrostatically assembled soft matter microsystems and illustrate how dynamical properties can be activated and sustained in microcompartmentalized media. PMID:26876162
Non-equilibrium behaviour in coacervate-based protocells under electric-field-induced excitation.
Yin, Yudan; Niu, Lin; Zhu, Xiaocui; Zhao, Meiping; Zhang, Zexin; Mann, Stephen; Liang, Dehai
2016-02-15
Although numerous strategies are now available to generate rudimentary forms of synthetic cell-like entities, minimal progress has been made in the sustained excitation of artificial protocells under non-equilibrium conditions. Here we demonstrate that the electric field energization of coacervate microdroplets comprising polylysine and short single strands of DNA generates membrane-free protocells with complex, dynamical behaviours. By confining the droplets within a microfluidic channel and applying a range of electric field strengths, we produce protocells that exhibit repetitive cycles of vacuolarization, dynamical fluctuations in size and shape, chaotic growth and fusion, spontaneous ejection and sequestration of matter, directional capture of solute molecules, and pulsed enhancement of enzyme cascade reactions. Our results highlight new opportunities for the study of non-equilibrium phenomena in synthetic protocells, provide a strategy for inducing complex behaviour in electrostatically assembled soft matter microsystems and illustrate how dynamical properties can be activated and sustained in microcompartmentalized media.
Non-equilibrium oxidation states of zirconium during early stages of metal oxidation
Ma, Wen; Yildiz, Bilge; Herbert, F. William; Senanayake, Sanjaya D.
2015-03-09
The chemical state of Zr during the initial, self-limiting stage of oxidation on single crystal zirconium (0001), with oxide thickness on the order of 1 nm, was probed by synchrotron x-ray photoelectron spectroscopy. Quantitative analysis of the Zr 3d spectrum by the spectrum reconstruction method demonstrated the formation of Zr{sup 1+}, Zr{sup 2+}, and Zr{sup 3+} as non-equilibrium oxidation states, in addition to Zr{sup 4+} in the stoichiometric ZrO{sub 2}. This finding resolves the long-debated question of whether it is possible to form any valence states between Zr{sup 0} and Zr{sup 4+} at the metal-oxide interface. The presence of local strong electric fields and the minimization of interfacial energy are assessed and demonstrated as mechanisms that can drive the formation of these non-equilibrium valence states of Zr.
NASA Astrophysics Data System (ADS)
Jiang, Shixiao W.; Lu, Haihao; Zhou, Douglas; Cai, David
2016-08-01
Characterizing dispersive wave turbulence in the long time dynamics is central to understanding of many natural phenomena, e.g., in atmosphere ocean dynamics, nonlinear optics, and plasma physics. Using the β-Fermi-Pasta-Ulam nonlinear system as a prototypical example, we show that in thermal equilibrium and non-equilibrium steady state the turbulent state even in the strongly nonlinear regime possesses an effective linear stochastic structure in renormalized normal variables. In this framework, we can well characterize the spatiotemporal dynamics, which are dominated by long-wavelength renormalized waves. We further demonstrate that the energy flux is nearly saturated by the long-wavelength renormalized waves in non-equilibrium steady state. The scenario of such effective linear stochastic dynamics can be extended to study turbulent states in other nonlinear wave systems.
Non-equilibrium oxidation states of zirconium during early stages of metal oxidation
Ma, Wen; Senanayake, Sanjaya D.; Herbert, F. William; Yildiz, Bilge
2015-03-11
The chemical state of Zr during the initial, self-limiting stage of oxidation on single crystal zirconium (0001), with oxide thickness on the order of 1 nm, was probed by synchrotron x-ray photoelectron spectroscopy. Quantitative analysis of the Zr 3d spectrum by the spectrum reconstruction method demonstrated the formation of Zr1+, Zr2+, and Zr3+ as non-equilibrium oxidation states, in addition to Zr4+ in the stoichiometric ZrO2. This finding resolves the long-debated question of whether it is possible to form any valence states between Zr0 and Zr4+ at the metal-oxide interface. As a result, the presence of local strong electric fields andmore » the minimization of interfacial energy are assessed and demonstrated as mechanisms that can drive the formation of these non-equilibrium valence states of Zr.« less
A non-equilibrium equation-of-motion approach to quantum transport utilizing projection operators
NASA Astrophysics Data System (ADS)
Ochoa, Maicol A.; Galperin, Michael; Ratner, Mark A.
2014-11-01
We consider a projection operator approach to the non-equilbrium Green function equation-of-motion (PO-NEGF EOM) method. The technique resolves problems of arbitrariness in truncation of an infinite chain of EOMs and prevents violation of symmetry relations resulting from the truncation (equivalence of left- and right-sided EOMs is shown and symmetry with respect to interchange of Fermi or Bose operators before truncation is preserved). The approach, originally developed by Tserkovnikov (1999 Theor. Math. Phys. 118 85) for equilibrium systems, is reformulated to be applicable to time-dependent non-equilibrium situations. We derive a canonical form of EOMs, thus explicitly demonstrating a proper result for the non-equilibrium atomic limit in junction problems. A simple practical scheme applicable to quantum transport simulations is formulated. We perform numerical simulations within simple models and compare results of the approach to other techniques and (where available) also to exact results.
Multiple scales approach to the gas-piston non-equilibrium themodynamics
NASA Astrophysics Data System (ADS)
Chiuchiù, D.; Gubbiotti, G.
2016-05-01
The non-equilibrium thermodynamics of a gas inside a piston is a conceptually simple problem where analytic results are rare. For example, it is hard to find in the literature analytic formulas that describe the heat exchanged with the reservoir when the system either relaxes to equilibrium or is compressed over a finite time. In this paper we derive this kind of analytic formula. To achieve this result, we take the equations derived by Cerino et al (2015 Phys. Rev. E 91 032128) describing the dynamic evolution of a gas-piston system, we cast them in a dimensionless form, and we solve the dimensionless equations with the multiple scales expansion method. With the approximated solutions we obtained, we express in a closed form the heat exchanged by the gas-piston system with the reservoir for a large class of relevant non-equilibrium situations.
Review of Non-Equilibrium Plasmadynamics to Predict Energy Transfer in Arcjet Thrusters
NASA Astrophysics Data System (ADS)
Krier, Herman
1998-10-01
Both chemical and thermal processes in an electrothermal arcjet are described as non-equilibrium. Arc current is converted to electron thermal energy through ohmic dissipation. The electrons transfer thermal energy to heavy species in the arc plasma through collisions. This energy is then converted to kinetic energy (and thrust) as the fluid accelerates through the nozzle. The paper presents an axisymmetric, steady, laminar, continuum flow model, supporting a two-temperature kinetic and chemical non-equilibrium, formulated for a direct current arcjet with variabe mixture ratios of nitrogen and hydrogen. Seven species (ions, atoms, electons) assumed with finite rate chemistry accounted for. The model predictions are compared to experiments with a NASA 1 kW hydrazine propellant arcjet.Background information.
Nanoscale temperature measurements using non-equilibrium Brownian dynamics of a levitated nanosphere
NASA Astrophysics Data System (ADS)
Millen, J.; Deesuwan, T.; Barker, P.; Anders, J.
2014-06-01
Einstein realized that the fluctuations of a Brownian particle can be used to ascertain the properties of its environment. A large number of experiments have since exploited the Brownian motion of colloidal particles for studies of dissipative processes, providing insight into soft matter physics and leading to applications from energy harvesting to medical imaging. Here, we use heated optically levitated nanospheres to investigate the non-equilibrium properties of the gas surrounding them. Analysing the sphere's Brownian motion allows us to determine the temperature of the centre-of-mass motion of the sphere, its surface temperature and the heated gas temperature in two spatial dimensions. We observe asymmetric heating of the sphere and gas, with temperatures reaching the melting point of the material. This method offers opportunities for accurate temperature measurements with spatial resolution on the nanoscale, and provides a means for testing non-equilibrium thermodynamics.
A synthetic playground for non-equilibrium error correction and information processing
NASA Astrophysics Data System (ADS)
Murugan, Arvind
2015-03-01
Biological proofreading mechanisms can lower error rates well below Boltzmann statistics by consuming free energy. By abstracting the principles behind these biochemical mechanisms, we discuss the central ingredients needed for any complex reaction network to perform error correction and the inherent energy-error tradeoffs. We propose that such abstract principles can be implemented and tested in synthetic systems using DNA strand displacement reactions. Such DNA circuits can mimic biochemical models of proofreading because of two central features: 1. exquisite control over reaction kinetics, 2. a DNA analog of ATP hydrolysis. Indeed, such DNA circuits may be used to mimic any non-equilibrium information processing scheme seen in biochemistry, such as adaption and ultra-sensitivity in addition to error correction. We discuss the conceptual and practical benefits from having a well-controlled synthetic playground for non-equilibrium ideas.
Low temperature superplasticity of AZ91 magnesium alloy with non-equilibrium grain boundaries
Mabuchi, M.; Ameyama, K.; Iwasaki, H.; Higashi, K.
1999-05-28
The superplastic behavior of a fine-grained AZ91 alloy, processed by equal channel angular extrusion, has been investigated in a low temperature range of 423--523 K. The experimental results showed a stress exponent of 2 and the activation energy for superplastic flow was in agreement with that for grain boundary diffusion of magnesium. The alloy with non-equilibrium grain boundary structures exhibited lower superplastic elongation than the alloy with equilibrium grain boundaries. Furthermore, the strain rate for superplastic flow of the former was lower than that of the latter. These differences probably arise because the accommodation process for grain boundary sliding is hampered by the long-range stresses associated with the non-equilibrium grain boundaries.
Non-equilibrium Dynamics in the Quantum Brownian Oscillator and the Second Law of Thermodynamics
NASA Astrophysics Data System (ADS)
Kim, Ilki
2012-01-01
We initially prepare a quantum linear oscillator weakly coupled to a bath in equilibrium at an arbitrary temperature. We disturb this system by varying a Hamiltonian parameter of the coupled oscillator, namely, either its spring constant or mass according to an arbitrary but pre-determined protocol in order to perform external work on it. We then derive a closed expression for the reduced density operator of the coupled oscillator along this non-equilibrium process as well as the exact expression pertaining to the corresponding quasi-static process. This immediately allows us to analytically discuss the second law of thermodynamics for non-equilibrium processes. Then we derive a Clausius inequality and obtain its validity supporting the second law, as a consistent generalization of the Clausius equality valid for the quasi-static counterpart, introduced in (Kim and Mahler in Phys. Rev. E 81:011101, 2010, [1]).
On Non-Equilibrium Thermodynamics of Space-Time and Quantum Gravity
NASA Astrophysics Data System (ADS)
Munkhammar, Joakim
Based on recent results from general relativistic statistical mechanics and black hole information transfer limits, a space-time entropy-action equivalence is proposed as a generalization of the holographic principle. With this conjecture, the action principle can be replaced by the second law of thermodynamics, and for the Einstein-Hilbert action the Einstein field equations are conceptually the result of thermodynamic equilibrium. For non-equilibrium situations, Jaynes' information-theoretic approach to maximum entropy production is adopted instead of the second law of thermodynamics. As it turns out for appropriate choices of constants, quantum gravity is obtained. For the special case of a free particle the Bekenstein-Verlinde entropy-to-displacement relation of holographic gravity and thus the traditional holographic principle emerges. Although Jacobson's original thermodynamic equilibrium approach proposed that gravity might not necessarily be quantized, this particular non-equilibrium treatment might require it.
Non-equilibrium model of spray-stratified atmospheric boundary layer under high wind conditions
NASA Astrophysics Data System (ADS)
Rastigejev, Yevgenii; Suslov, Sergey
2014-11-01
Tropical cyclone is a complex meteorological phenomenon which dynamics is defined by a wide variety of factors including exchange of momentum, heat and moisture between the atmosphere and the ocean. Ocean spray plays an important role in this air-sea interaction. Here we developed a two-temperature non-equilibrium variable density (non-Bousinessq) turbulence closure model to describe the ocean spray-stratified hurricane boundary layer structure and dynamics. The model consistently describes a two-way coupling between mechanical and thermodynamic influences of the ocean spray. The obtained results confirm that the impact of non-equilibrium effects is significant over the complete range of possible spray concentration values, therefore has to be included into a consistent parameterization of moisture, heat and momentum transfer process over the ocean under high wind condition of a hurricane. NSF HRD-1036563.
[Use of ionizing radiation sources in metallurgy: risk assessment].
Giugni, U
2012-01-01
Use of ionizing radiation sources in the metallurgical industry: risk assessment. Radioactive sources and fixed or mobile X-ray equipment are used for both process and quality control. The use of ionizing radiation sources requires careful risk assessment. The text lists the characteristics of the sources and the legal requirements, and contains a description of the documentation required and the methods used for risk assessment. It describes how to estimate the doses to operators and the relevant classification criteria used for the purpose of radiation protection. Training programs must be organized in close collaboration between the radiation protection expert and the occupational physician.
The development of a non-equilibrium dispersed flow film boiling heat transfer modeling package
NASA Astrophysics Data System (ADS)
Meholic, Michael J.
The dispersed flow film boiling (DFFB) heat transfer regime is important to several applications including cryogenics, rocket engines, steam generators, and in the safety analysis of nuclear reactors. Most notably, DFFB is responsible for the heat transfer during the blowdown and reflood portions of the postulated loss-of-coolant-accident (LOCA). Such analyses require the accurate predictions of the heat transfer resulting from the non-equilibrium conditions present in DFFB. A total of six, interrelated heat transfer paths need to be modeled accurately in order to quantify DFFB heat transfer. Within the nuclear industry, transient safety analysis codes, such as COBRA-TF, are used to ensure the safety of the reactor under various transient and accident scenarios. An extensive literature review of DFFB heat transfer highlighted a number of correlative, phenomenological, and mechanistic models. The Forslund-Rohsenow model is most commonly implemented throughout the nuclear industry. However, several of the models suggested by Forslund and Rohsenow to model DFFB phenomena are either inapplicable for nuclear reactors or do not provide an accurate physical representation of the true situation. Deficiencies among other DFFB heat transfer models in their applicability to nuclear reactors or in their computational expenses motivated the development of a mechanistically based DFFB model which accounted for each heat transfer mechanism explicitly. The heat transfer resulting from dispersed droplets contacting the heated wall in DFFB was often neglected in previous models. In this work, a first-principles approach was implemented to quantify the heat transfer attributed to direct contact. Lagrangian droplet trajectory calculations incorporating realistic radial vapor velocity and temperature profiles were performed to determine if droplets could contact the heated wall based upon the local conditions. These calculations were performed over a droplet size spectrum accounting
The non-equilibrium allele frequency spectrum in a Poisson random field framework.
Kaj, Ingemar; Mugal, Carina F
2016-10-01
In population genetic studies, the allele frequency spectrum (AFS) efficiently summarizes genome-wide polymorphism data and shapes a variety of allele frequency-based summary statistics. While existing theory typically features equilibrium conditions, emerging methodology requires an analytical understanding of the build-up of the allele frequencies over time. In this work, we use the framework of Poisson random fields to derive new representations of the non-equilibrium AFS for the case of a Wright-Fisher population model with selection. In our approach, the AFS is a scaling-limit of the expectation of a Poisson stochastic integral and the representation of the non-equilibrium AFS arises in terms of a fixation time probability distribution. The known duality between the Wright-Fisher diffusion process and a birth and death process generalizing Kingman's coalescent yields an additional representation. The results carry over to the setting of a random sample drawn from the population and provide the non-equilibrium behavior of sample statistics. Our findings are consistent with and extend a previous approach where the non-equilibrium AFS solves a partial differential forward equation with a non-traditional boundary condition. Moreover, we provide a bridge to previous coalescent-based work, and hence tie several frameworks together. Since frequency-based summary statistics are widely used in population genetics, for example, to identify candidate loci of adaptive evolution, to infer the demographic history of a population, or to improve our understanding of the underlying mechanics of speciation events, the presented results are potentially useful for a broad range of topics.
Turbulent mixing and beyond: non-equilibrium processes from atomistic to astrophysical scales I
Abarzhi, S. I.; Gauthier, S.; Sreenivasan, K. R.
2013-01-01
In this Introduction, we summarize and provide a perspective on 11 articles on ‘Turbulent mixing and beyond’. The papers represent the broad variety of themes of the subject, and are concerned with fundamental aspects of turbulence, mixing and non-equilibrium dynamics. While each paper deals with a specific problem, the collection gives a panoramic overview of the subject at its present state of understanding. PMID:23185063
Direct-Numerical and Large-Eddy Simulations of a Non-Equilibrium Turbulent Kolmogorov Flow
NASA Technical Reports Server (NTRS)
Woodruff, S. L.; Shebalin, J. V.; Hussaini, M. Y.
1999-01-01
A non-equilibrium form of turbulent Kolmogorov flow is set up by making an instantaneous change in the amplitude of the spatially-periodic forcing. It is found that the response of the flow to this instantaneous change becomes more dramatic as the wavenumber of the forcing is increased, and, at the same time, that the faithfulness with which the large-eddy-simulation results agree with the direct-numerical results decreases.
The non-equilibrium allele frequency spectrum in a Poisson random field framework.
Kaj, Ingemar; Mugal, Carina F
2016-10-01
In population genetic studies, the allele frequency spectrum (AFS) efficiently summarizes genome-wide polymorphism data and shapes a variety of allele frequency-based summary statistics. While existing theory typically features equilibrium conditions, emerging methodology requires an analytical understanding of the build-up of the allele frequencies over time. In this work, we use the framework of Poisson random fields to derive new representations of the non-equilibrium AFS for the case of a Wright-Fisher population model with selection. In our approach, the AFS is a scaling-limit of the expectation of a Poisson stochastic integral and the representation of the non-equilibrium AFS arises in terms of a fixation time probability distribution. The known duality between the Wright-Fisher diffusion process and a birth and death process generalizing Kingman's coalescent yields an additional representation. The results carry over to the setting of a random sample drawn from the population and provide the non-equilibrium behavior of sample statistics. Our findings are consistent with and extend a previous approach where the non-equilibrium AFS solves a partial differential forward equation with a non-traditional boundary condition. Moreover, we provide a bridge to previous coalescent-based work, and hence tie several frameworks together. Since frequency-based summary statistics are widely used in population genetics, for example, to identify candidate loci of adaptive evolution, to infer the demographic history of a population, or to improve our understanding of the underlying mechanics of speciation events, the presented results are potentially useful for a broad range of topics. PMID:27378747
Search for a non-equilibrium plasma in the merging galaxy cluster Abell 754
NASA Astrophysics Data System (ADS)
Inoue, Shota; Hayashida, Kiyoshi; Ueda, Shutaro; Nagino, Ryo; Tsunemi, Hiroshi; Koyama, Katsuji
2016-06-01
Abell 754 is a galaxy cluster in which an ongoing merger is evident on the plane of the sky, from the southeast to the northwest. We study the spatial variation of the X-ray spectra observed with Suzaku along the merging direction, centering on the Fe Ly α/Fe He α line ratio to search for possible deviation from ionization equilibrium. Fitting with a single-temperature collisional non-equilibrium plasma model shows that the electron temperature increases from the southeast to the northwest. The ionization parameter is consistent with that in equilibrium (net > 1013 s cm-3) except for the specific region with the highest temperature (kT=13.3_{-1.1}^{+1.4}keV) where n_et=10^{11.6_{-1.7}^{+0.6}}s cm-3. The elapsed time from the plasma heating estimated from the ionization parameter is 0.36-76 Myr at the 90% confidence level. This timescale is quite short but consistent with the traveling time of a shock to pass through that region. We thus interpret that the non-equilibrium ionization plasma in Abell 754 observed is a remnant of the shock heating in the merger process. However, we note that the X-ray spectrum of the specific region where the non-equilibrium is found can also be fitted with a collisional ionization plasma model with two temperatures, low kT=4.2^{+4.2}_{-1.5}keV and very high kT >19.3 keV. The very high temperature component is alternatively fitted with a power-law model. Either of these spectral models is interpreted as a consequence of the ongoing merger process as in the case of the non-equilibrium ionization plasma.
Non-equilibrium growth patterns of carbohydrate and saccharin in gel media
NASA Astrophysics Data System (ADS)
Das, Ishwar; Sharma, Archana; Kumar, Anuj; Lall, R. S.
1997-02-01
Non-equilibrium growth patterns of mono-, di-saccharides and a sweetener saccharin have been developed on microslides in the presence of a dense matrix. Scanned pictures were analyzed and fractal dimensions calculated by a box counting method. Morphologies and fractal dimension were found to depend on the compound-dense matrix composition. In case of di-saccharides, the morphology depends on a linkage between the monomer units.
An Initial Non-Equilibrium Porous-Media Model for CFD Simulation of Stirling Regenerators
NASA Technical Reports Server (NTRS)
Tew, Roy C.; Simon, Terry; Gedeon, David; Ibrahim, Mounir; Rong, Wei
2006-01-01
The objective of this paper is to define empirical parameters for an initial thermal non-equilibrium porous-media model for use in Computational Fluid Dynamics (CFD) codes for simulation of Stirling regenerators. The two codes currently used at Glenn Research Center for Stirling modeling are Fluent and CFD-ACE. The codes porous-media models are equilibrium models, which assume solid matrix and fluid are in thermal equilibrium. This is believed to be a poor assumption for Stirling regenerators; Stirling 1-D regenerator models, used in Stirling design, use non-equilibrium regenerator models and suggest regenerator matrix and gas average temperatures can differ by several degrees at a given axial location and time during the cycle. Experimentally based information was used to define: hydrodynamic dispersion, permeability, inertial coefficient, fluid effective thermal conductivity, and fluid-solid heat transfer coefficient. Solid effective thermal conductivity was also estimated. Determination of model parameters was based on planned use in a CFD model of Infinia's Stirling Technology Demonstration Converter (TDC), which uses a random-fiber regenerator matrix. Emphasis is on use of available data to define empirical parameters needed in a thermal non-equilibrium porous media model for Stirling regenerator simulation. Such a model has not yet been implemented by the authors or their associates.
A study of non-equilibrium phonons in GaAs/AlAs quantum wells
Su, Zhenpeng
1996-11-01
In this thesis we have studied the non-equilibrium phonons in GaAs/AlAs quantum wells via Raman scattering. We have demonstrated experimentally that by taking into account the time-reversal symmetry relation between the Stokes and anti-Stokes Raman cross sections, one can successfully measure the non-equilibrium phonon occupancy in quantum wells. Using this technique, we have studied the subject of resonant intersubband scattering of optical phonons. We find that interface roughness plays an important role in resonant Raman scattering in quantum wells. The lateral size of the smooth regions in such interface is estimated to be of the order of 100 {Angstrom}. Through a study of photoluminescence of GaAs/AlAs quantum wells under high intensity laser excitation, we have found that band nonparabolicity has very little effect on the electron subband energies even for subbands as high as a few hundred meV above the lowest one. This finding may require additional theoretical study to understand its origin. We have also studied phonon confinement and propagation in quantum wells. We show that Raman scattering of non-equilibrium phonons in quantum wells can be a sensitive measure of the spatial extent of the longitudinal optical (LO) phonons. We deduce the coherence length of LO phonons in GaAs/Al{sub x}Ga{sub 1-x}As quantum wells as a function of the Al concentration x.
Reaction and internal energy relaxation rates in viscous thermochemically non-equilibrium gas flows
Kustova, E. V.; Oblapenko, G. P.
2015-01-15
In the present paper, reaction and energy relaxation rates as well as the normal stress are studied for viscous gas flows with vibrational and chemical non-equilibrium. Using the modified Chapman-Enskog method, multi-temperature models based on the Treanor and Boltzmann vibrational distributions are developed for the general case taking into account all kinds of vibrational energy transitions, exchange reactions, dissociation, and recombination. Integral equations specifying the first-order corrections to the normal mean stress and reaction rates are derived, as well as approximate systems of linear equations for their numerical computation. Generalized thermodynamic driving forces associated with all non-equilibrium processes are introduced. It is shown that normal stresses and rates of non-equilibrium processes can be expressed in terms of the same driving forces; the symmetry of kinetic coefficients in these expressions is proven. The developed general model is applied to a particular case of a pure N{sub 2} viscous flow with slow VT relaxation. Normal stress and rates of vibrational relaxation are studied for various ratios of vibrational and translational temperatures. The cross effects between different vibrational transitions in viscous flows are evaluated, along with the influence of anharmonicity and flow compressibility on the first-order corrections to the relaxation rate. Limits of validity for the widely used Landau–Teller model of vibrational relaxation are indicated.
Göppel, Tobias; Palyulin, Vladimir V; Gerland, Ulrich
2016-07-27
An out-of-equilibrium physical environment can drive chemical reactions into thermodynamically unfavorable regimes. Under prebiotic conditions such a coupling between physical and chemical non-equilibria may have enabled the spontaneous emergence of primitive evolutionary processes. Here, we study the coupling efficiency within a theoretical model that is inspired by recent laboratory experiments, but focuses on generic effects arising whenever reactant and product molecules have different transport coefficients in a flow-through system. In our model, the physical non-equilibrium is represented by a drift-diffusion process, which is a valid coarse-grained description for the interplay between thermophoresis and convection, as well as for many other molecular transport processes. As a simple chemical reaction, we consider a reversible dimerization process, which is coupled to the transport process by different drift velocities for monomers and dimers. Within this minimal model, the coupling efficiency between the non-equilibrium transport process and the chemical reaction can be analyzed in all parameter regimes. The analysis shows that the efficiency depends strongly on the Damköhler number, a parameter that measures the relative timescales associated with the transport and reaction kinetics. Our model and results will be useful for a better understanding of the conditions for which non-equilibrium environments can provide a significant driving force for chemical reactions in a prebiotic setting.
A simple non-equilibrium theory of non-contact dissipation force microscopy
NASA Astrophysics Data System (ADS)
Kantorovich, L. N.
2001-02-01
The tip-surface interaction in the non-contact atomic force microscopy (NC-AFM) leads to energy dissipation. Recently, this effect has been harnessed to obtain images with atomic resolution. In an important paper Gauthier and Tsukada (GT) (1999 Phys. Rev. B 60 11716) suggested a theory of this, so-called non-contact dissipation force microscopy (NC-DFM) using a stochastic approach within a simple one-atomic representation of the surface. In this paper we elaborate on this model further, stressing the importance of a consistent non-equilibrium consideration. Then, using a more general model, we offer an alternative derivation based on a rather simple approach to non-equilibrium phenomenon used by Kirkwood for the Brownian motion. We show that our method leads to the final result similar to that obtained in the GT paper. We also discuss some other models for the energy dissipation in NC-AFM. In particular, we emphasise that the `stick and slip' (or adhesion hysteresis) model of energy dissipation, although containing a specific element which requires additional features to be incorporated in our model, is to be considered using non-equilibrium methods.
Rapid non-equilibrium turnover fluidizes entangled F-actin solutions
NASA Astrophysics Data System (ADS)
McCall, Patrick M.; Kovar, David R.; Gardel, Margaret L.
The actin cytoskeleton of living cells is a semiflexible polymer network which regulates cell division, motility, and morphogenesis by controlling cell shape. These complex shape-changing processes require both mechanical deformation and remodeling of the actin cytoskeleton. Molecular motors generate internal forces to drive deformation, while cytoskeletal remodeling is regulated by non-equilibrium polymer turnover. Although the mechanical properties of equilibrium actin filament (F-actin) networks are well-described by theories of semiflexible polymers, these theories do not incorporate the effects of non-equilibrium turnover. To address this experimentally, we developed a model system in which both the turnover rate and the length distribution of purified F-actin can be tuned independently at steady-state through the combined action of actin regulatory proteins. Specifically we tune the concentrations of cofilin, profilin, and formin to regulate F-actin severing, recycling, and nucleation, respectively. We find that the actin turnover rate can be tuned by cofilin up to 25-fold (31 +/- 2 subunits/sec/filament). Surprisingly, changes in turnover rate have no effect on the steady-state F-actin length distribution, which is instead set by formin concentration. Passive microrheology measurements show that increased turnover leads to striking fluidization in both entangled and crosslinked networks. Non-equilibrium turnover thus enables modulation of network mechanics, which impacts force transmission and material deformation.
Shock and Laser Induced Non-Equilibrium Chemistry in Molecular Energetics
NASA Astrophysics Data System (ADS)
Wood, Mitchell; Cherukara, Mathew; Kober, Edward; Strachan, Alejandro
2015-06-01
In this study, we have used large scale reactive molecular dynamics (MD) simulations to study how contrasting initiation mechanisms from either shock or electromagnetic insults compare to traditional thermal initiation. We will show how insults of equal strength but different character can yield vastly different reaction profiles and thus the evolution of hot-spots. For shocked RDX (Up = 2km/s), we find that the collapse of a cylindrical 40 nm diameter pore leads to a significant amount of non-equilibrium reactions followed by the formation of a sustained deflagration wave. In contrast, a hot spot that is seeded into a statically compressed crystal with matching size and temperature will quench over the same timescale, highlighting the importance of insult type. Furthermore, MD simulations of electromagnetic insults coupled to intramolecular vibrations have shown, in some cases, mode specific initial chemistry and altered kinetics of the subsequent decomposition. By leveraging spectroscopic and chemical information gathered in our MD simulations, we have been able to identify and track non-equilibrium vibrational states of these materials and correlate them to these observed changes. Implications of insult dependent reactivity and non-equilibrium chemistry will be discussed.
Cerbino, Roberto; Sun, Yifei; Donev, Aleksandar; Vailati, Alberto
2015-01-01
Diffusion processes are widespread in biological and chemical systems, where they play a fundamental role in the exchange of substances at the cellular level and in determining the rate of chemical reactions. Recently, the classical picture that portrays diffusion as random uncorrelated motion of molecules has been revised, when it was shown that giant non-equilibrium fluctuations develop during diffusion processes. Under microgravity conditions and at steady-state, non-equilibrium fluctuations exhibit scale invariance and their size is only limited by the boundaries of the system. In this work, we investigate the onset of non-equilibrium concentration fluctuations induced by thermophoretic diffusion in microgravity, a regime not accessible to analytical calculations but of great relevance for the understanding of several natural and technological processes. A combination of state of the art simulations and experiments allows us to attain a fully quantitative description of the development of fluctuations during transient diffusion in microgravity. Both experiments and simulations show that during the onset the fluctuations exhibit scale invariance at large wave vectors. In a broader range of wave vectors simulations predict a spinodal-like growth of fluctuations, where the amplitude and length-scale of the dominant mode are determined by the thickness of the diffuse layer. PMID:26419420
NASA Astrophysics Data System (ADS)
Cerbino, Roberto; Sun, Yifei; Donev, Aleksandar; Vailati, Alberto
2015-09-01
Diffusion processes are widespread in biological and chemical systems, where they play a fundamental role in the exchange of substances at the cellular level and in determining the rate of chemical reactions. Recently, the classical picture that portrays diffusion as random uncorrelated motion of molecules has been revised, when it was shown that giant non-equilibrium fluctuations develop during diffusion processes. Under microgravity conditions and at steady-state, non-equilibrium fluctuations exhibit scale invariance and their size is only limited by the boundaries of the system. In this work, we investigate the onset of non-equilibrium concentration fluctuations induced by thermophoretic diffusion in microgravity, a regime not accessible to analytical calculations but of great relevance for the understanding of several natural and technological processes. A combination of state of the art simulations and experiments allows us to attain a fully quantitative description of the development of fluctuations during transient diffusion in microgravity. Both experiments and simulations show that during the onset the fluctuations exhibit scale invariance at large wave vectors. In a broader range of wave vectors simulations predict a spinodal-like growth of fluctuations, where the amplitude and length-scale of the dominant mode are determined by the thickness of the diffuse layer.
NASA Astrophysics Data System (ADS)
Lucia, Umberto
2016-02-01
The balance of forces and processes between the system and the environment and the processes inside the system are the result of the flows of the quanta. Moreover, the transition between two thermodynamic states is the consequence of absorption or emission of quanta, but, during the transition, the entropy variation due to the irreversibility occurs and it breaks any symmetry of time. Consequently, the irreversibility is the result of a transition, a process, an interaction between the system and its environment. This interaction results completely time-irreversible for any real process because of irreversibility. As a consequence, a proof of the third law is obtained proving that the zero temperature state can be achieved only for an infinite work lost for dissipation or in an infinite time. The fundamental role of time both in equilibrium and in non equilibrium analysis is pointed out. Moreover, the non equilibrium temperature is related to the entropy generation and its fluctuation rate; indeed, non-stationary temperature means that the system has not yet attained free energy minimum state, i.e., the maximum entropy state; the consequence is that the zero temperature state can be achieved only for an infinite work lost for dissipation or in an infinite time. In engineering thermodynamics the efficiency is always obtained without any consideration on time, while, here, just the time is introduced as a fundamental quantity of the analysis of non equilibrium states.
Universality of non-equilibrium fluctuations in strongly correlated quantum liquids
NASA Astrophysics Data System (ADS)
Ferrier, Meydi; Arakawa, Tomonori; Hata, Tokuro; Fujiwara, Ryo; Delagrange, Raphaëlle; Weil, Raphaël; Deblock, Richard; Sakano, Rui; Oguri, Akira; Kobayashi, Kensuke
2016-03-01
Interacting quantum many-body systems constitute a fascinating research field because they form quantum liquids with remarkable properties and universal behaviour. In fermionic systems, such quantum liquids are realized in helium-3 liquid, heavy fermion systems, neutron stars and cold gases. Their properties in the linear-response regime have been successfully described by the theory of Fermi liquids. The idea is that they behave as an ensemble of non-interacting `quasi-particles’. However, non-equilibrium properties have still to be established and remain a key issue of many-body physics. Here, we show a precise experimental demonstration of Landau Fermi liquid theory extended to the non-equilibrium regime in a zero-dimensional system. Combining transport and ultra-sensitive current noise measurements, we have unambiguously identified the SU(2) (ref. ) and SU(4) (refs ,,,,) symmetries of a quantum liquid in a carbon nanotube tuned in the universal Kondo regime. Whereas the free quasi-particle picture is found valid around equilibrium, an enhancement of the current fluctuations is detected out of equilibrium and perfectly explained by an effective charge induced by the residual interaction between quasi-particles. Moreover, an as-yet-unknown scaling law for the effective charge is discovered, suggesting a new non-equilibrium universality. Our method paves a new way to explore the exotic nature of quantum liquids out of equilibrium through their fluctuations in a wide variety of physical systems.
Space charge corrected electron emission from an aluminum surface under non-equilibrium conditions
Wendelen, W.; Bogaerts, A.; Mueller, B. Y.; Rethfeld, B.; Autrique, D.
2012-06-01
A theoretical study has been conducted of ultrashort pulsed laser induced electron emission from an aluminum surface. Electron emission fluxes retrieved from the commonly employed Fowler-DuBridge theory were compared to fluxes based on a laser-induced non-equilibrium electron distribution. As a result, the two- and three-photon photoelectron emission parameters for the Fowler-DuBridge theory have been approximated. We observe that at regimes where photoemission is important, laser-induced electron emission evolves in a more smooth manner than predicted by the Fowler-DuBridge theory. The importance of the actual electron distribution decreases at higher laser fluences, whereas the contribution of thermionic emission increases. Furthermore, the influence of a space charge effect on electron emission was evaluated by a one dimensional particle-in-cell model. Depending on the fluences, the space charge reduces the electron emission by several orders of magnitude. The influence of the electron emission flux profiles on the effective electron emission was found to be negligible. However, a non-equilibrium electron velocity distribution increases the effective electron emission significantly. Our results show that it is essential to consider the non-equilibrium electron distribution as well as the space charge effect for the description of laser-induced photoemission.
Ge, Hao; Qian, Hong
2011-01-01
A theory for an non-equilibrium phase transition in a driven biochemical network is presented. The theory is based on the chemical master equation (CME) formulation of mesoscopic biochemical reactions and the mathematical method of large deviations. The large deviations theory provides an analytical tool connecting the macroscopic multi-stability of an open chemical system with the multi-scale dynamics of its mesoscopic counterpart. It shows a corresponding non-equilibrium phase transition among multiple stochastic attractors. As an example, in the canonical phosphorylation-dephosphorylation system with feedback that exhibits bistability, we show that the non-equilibrium steady-state (NESS) phase transition has all the characteristics of classic equilibrium phase transition: Maxwell construction, a discontinuous first-derivative of the 'free energy function', Lee-Yang's zero for a generating function and a critical point that matches the cusp in nonlinear bifurcation theory. To the biochemical system, the mathematical analysis suggests three distinct timescales and needed levels of description. They are (i) molecular signalling, (ii) biochemical network nonlinear dynamics, and (iii) cellular evolution. For finite mesoscopic systems such as a cell, motions associated with (i) and (iii) are stochastic while that with (ii) is deterministic. Both (ii) and (iii) are emergent properties of a dynamic biochemical network.
Ge, Hao; Qian, Hong
2011-01-01
A theory for an non-equilibrium phase transition in a driven biochemical network is presented. The theory is based on the chemical master equation (CME) formulation of mesoscopic biochemical reactions and the mathematical method of large deviations. The large deviations theory provides an analytical tool connecting the macroscopic multi-stability of an open chemical system with the multi-scale dynamics of its mesoscopic counterpart. It shows a corresponding non-equilibrium phase transition among multiple stochastic attractors. As an example, in the canonical phosphorylation–dephosphorylation system with feedback that exhibits bistability, we show that the non-equilibrium steady-state (NESS) phase transition has all the characteristics of classic equilibrium phase transition: Maxwell construction, a discontinuous first-derivative of the ‘free energy function’, Lee–Yang's zero for a generating function and a critical point that matches the cusp in nonlinear bifurcation theory. To the biochemical system, the mathematical analysis suggests three distinct timescales and needed levels of description. They are (i) molecular signalling, (ii) biochemical network nonlinear dynamics, and (iii) cellular evolution. For finite mesoscopic systems such as a cell, motions associated with (i) and (iii) are stochastic while that with (ii) is deterministic. Both (ii) and (iii) are emergent properties of a dynamic biochemical network. PMID:20466813
NASA Astrophysics Data System (ADS)
Qu, Zhiguo; Xu, Huijin; Tao, Wenquan
Numerical simulation with the Forchheimer flow model and local thermal non-equilibrium model for porous region is performed on forced convective heat transfer in a tube partially filled with metallic foams. Flow and heat transfer of fluid in the hollow region and those of fluid in the porous region are conjugated together via the coupling conditions at porous-fluid interface. A heat flow model is proposed with special numerical treatments employed for non-equilibrium conjugated heat transfer in foam-fluid system. Velocity and temperature profiles in the flow direction are obtained and validated with analytical results. Effects of porosity, pore density, dimensionless interfacial radius and fluid-to-solid thermal conductivity ratio on flow characteristics and thermal performance are examined. Accordingly, the entrance effect is analyzed through the numerical simulation in terms of both flow and heat transfer. The present tube exhibits more excellent heat transfer performance at the expense of moderate pressure drop compared with the tube without porous material. The numerical work is not only developed for forced convection in metal-foam partially filled tube, but can also be extended to similar problem with porous-fluid interface for other porous media with significant thermal non-equilibrium effect.
Cerbino, Roberto; Sun, Yifei; Donev, Aleksandar; Vailati, Alberto
2015-01-01
Diffusion processes are widespread in biological and chemical systems, where they play a fundamental role in the exchange of substances at the cellular level and in determining the rate of chemical reactions. Recently, the classical picture that portrays diffusion as random uncorrelated motion of molecules has been revised, when it was shown that giant non-equilibrium fluctuations develop during diffusion processes. Under microgravity conditions and at steady-state, non-equilibrium fluctuations exhibit scale invariance and their size is only limited by the boundaries of the system. In this work, we investigate the onset of non-equilibrium concentration fluctuations induced by thermophoretic diffusion in microgravity, a regime not accessible to analytical calculations but of great relevance for the understanding of several natural and technological processes. A combination of state of the art simulations and experiments allows us to attain a fully quantitative description of the development of fluctuations during transient diffusion in microgravity. Both experiments and simulations show that during the onset the fluctuations exhibit scale invariance at large wave vectors. In a broader range of wave vectors simulations predict a spinodal-like growth of fluctuations, where the amplitude and length-scale of the dominant mode are determined by the thickness of the diffuse layer. PMID:26419420
Reaction and internal energy relaxation rates in viscous thermochemically non-equilibrium gas flows
NASA Astrophysics Data System (ADS)
Kustova, E. V.; Oblapenko, G. P.
2015-01-01
In the present paper, reaction and energy relaxation rates as well as the normal stress are studied for viscous gas flows with vibrational and chemical non-equilibrium. Using the modified Chapman-Enskog method, multi-temperature models based on the Treanor and Boltzmann vibrational distributions are developed for the general case taking into account all kinds of vibrational energy transitions, exchange reactions, dissociation, and recombination. Integral equations specifying the first-order corrections to the normal mean stress and reaction rates are derived, as well as approximate systems of linear equations for their numerical computation. Generalized thermodynamic driving forces associated with all non-equilibrium processes are introduced. It is shown that normal stresses and rates of non-equilibrium processes can be expressed in terms of the same driving forces; the symmetry of kinetic coefficients in these expressions is proven. The developed general model is applied to a particular case of a pure N2 viscous flow with slow VT relaxation. Normal stress and rates of vibrational relaxation are studied for various ratios of vibrational and translational temperatures. The cross effects between different vibrational transitions in viscous flows are evaluated, along with the influence of anharmonicity and flow compressibility on the first-order corrections to the relaxation rate. Limits of validity for the widely used Landau-Teller model of vibrational relaxation are indicated.
A numerical model of non-equilibrium thermal plasmas. II. Governing equations
Li HePing; Zhang XiaoNing; Xia Weidong
2013-03-15
Governing equations and the corresponding physical properties of the plasmas are both prerequisites for studying the fundamental processes in a non-equilibrium thermal plasma system numerically. In this paper, a kinetic derivation of the governing equations used for describing the complicated thermo-electro-magneto-hydrodynamic-chemical coupling effects in non-equilibrium thermal plasmas is presented. This derivation, which is achieved using the Chapman-Enskog method, is completely consistent with the theory of the transport properties reported in the previous paper by the same authors. It is shown, based on this self-consistent theory, that the definitions of the specific heat at constant pressure and the reactive thermal conductivity of two-temperature plasmas are not necessary. The governing equations can be reduced to their counterparts under local thermodynamic equilibrium (LTE) and local chemical equilibrium (LCE) conditions. The general method for the determination of the boundary conditions of the solved variables is also discussed briefly. The two papers establish a self-consistent physical-mathematical model that describes the complicated physical and chemical processes in a thermal plasma system for the cases both in LTE or LCE conditions and under non-equilibrium conditions.
Cerbino, Roberto; Sun, Yifei; Donev, Aleksandar; Vailati, Alberto
2015-09-30
Diffusion processes are widespread in biological and chemical systems, where they play a fundamental role in the exchange of substances at the cellular level and in determining the rate of chemical reactions. Recently, the classical picture that portrays diffusion as random uncorrelated motion of molecules has been revised, when it was shown that giant non-equilibrium fluctuations develop during diffusion processes. Under microgravity conditions and at steady-state, non-equilibrium fluctuations exhibit scale invariance and their size is only limited by the boundaries of the system. In this work, we investigate the onset of non-equilibrium concentration fluctuations induced by thermophoretic diffusion in microgravity, a regime not accessible to analytical calculations but of great relevance for the understanding of several natural and technological processes. A combination of state of the art simulations and experiments allows us to attain a fully quantitative description of the development of fluctuations during transient diffusion in microgravity. Both experiments and simulations show that during the onset the fluctuations exhibit scale invariance at large wave vectors. In a broader range of wave vectors simulations predict a spinodal-like growth of fluctuations, where the amplitude and length-scale of the dominant mode are determined by the thickness of the diffuse layer.
NASA Astrophysics Data System (ADS)
Bondi, James F.
Over the past decade, the role of inorganic nanomaterials has become an essential cornerstone for modern research applications. Despite these applications becoming progressively more advanced, the field of nanoscience is dependent on a material's physical and chemical properties which are affected by factors such as size, shape, composition, and crystal structure. One synthetic approach to yield inorganic nanomaterials with great control is solution-based methods, particularly the reduction of metal salt precursors. Non-equilibrium phases and early transition metals represent one class of materials that may result in new and enhanced properties at the nanoscale but are challenging to synthesize. In this dissertation, I present my studies on synthesizing non-equilibrium intermetallics and early transition metal nanoparticles using n-butyllithium and solution-based methods. By utilizing a template-driven approach, I first report an optimized synthesis for the non-equilibrium L12-type Au 3M1-x ( M = Fe, Co, or Ni) intermetallics with morphological, compositional, and structural control. Modifying a previous n-butyllithium procedure, it was possible to identify key variables (solvent, order of reagent addition, stabilizer, and heating rate) which led to the generation of high phase purity and increased sample sizes. Aliquot studies showed that the intermetallic nanoparticles were formed through the initial nucleation of Au nanoparticles, followed by subsequent incorporation of the 3d transition metal. Property studies of the non-equilibrium phases found that Au3Fe1- x and Au3Co1-x nanoparticles are superparamagnetic with TB = 7.9 K and 2.4 K, respectively, while Au3Ni 1-x is weakly paramagnetic down to 1.8 K. Elemental analysis by energy dispersive X-ray spectroscopy and refinement of electron diffraction patterns confirmed Au3Fe1- x with a composition of approximately Au3Fe 0.7. The 3d transition metal deficiency in the non-equilibrium Au3 M1-x phases was studied by
Development of unified Reynolds stress models for non-equilibrium turbulent flows
NASA Astrophysics Data System (ADS)
Xu, Xiang-Hua
Turbulence modeling has played a major role in the calculation of turbulent flows of engineering importance. To solve the flow problems that arise in both nature and engineering, a variety of Reynolds stress models--including simple eddy viscosity models based on the Prandtl mixing length hypothesis, one-equation and two-equation models, nonlinear two-equation and explicit algebraic stress models, as well as full second-order closures--have been proposed during the past few decades. These models, which are typically based on benchmark near-equilibrium turbulence experimental data, perform fairly well in a variety of turbulent flows that are not far from equilibrium. However, it is now well recognized that these models cannot correctly predict turbulent flows that are far from equilibrium. In this dissertation, it is shown that they cannot even properly predict homogeneous turbulent flows that are in strongly strained non-equilibrium states. Two benchmark flows--homogeneous turbulent shear flow and homogeneous plane strain turbulence--are chosen to evaluate the performance of existing turbulence models since these two benchmark flows constitute idealizations of real engineering turbulent flows. It is found that none of the existing Reynolds stress models (including a recent version of a non-equilibrium, near-wall model) can predict results that compare favorably with Rapid Distortion Theory (RDT) in strongly distorted turbulent flows that are far from equilibrium. Moreover, it is demonstrated that the standard linear and nonlinear two-equation models can predict enormous negative values of the normal Reynolds stresses in non-equilibrium homogeneous turbulence that strongly violate basic realizability constraints. In light of the poor performance of existing Reynolds stress models in non-equilibrium homogeneous turbulence, two new Reynolds stress models are developed herein--an explicit algebraic stress model and a full second-order closure--that can correctly
Radiating electron source generation in ultraintense laser-foil interactions
NASA Astrophysics Data System (ADS)
Capdessus, R.; King, M.; McKenna, P.
2016-08-01
A radiating electron source is shown to be created by a laser pulse (with intensity of 1023 W/cm2 and duration equal to 30 fs) interacting with a near-critical density plasma. It is shown that the back radiation reaction resulting from high energy synchrotron radiation tends to counteract the action of the ponderomotive force. This enhances the collective dynamics of the radiating electrons in the highest field areas, resulting in the production of a compact radiation source (containing 80% of the synchrotron radiation emission), with an energy on the order of tens of MeV over the laser pulse duration. These phenomena are investigated using a QED-particle-in-cell code, and compared with a kinetic model accounting for the radiation reaction force in the electron distribution function. The results shed new light on electron-photon sources at ultra-high laser intensities and could be tested on future laser facilities.
Detailed observations of the source of terrestrial narrowband electromagnetic radiation
NASA Technical Reports Server (NTRS)
Kurth, W. S.
1982-01-01
Detailed observations are presented of a region near the terrestrial plasmapause where narrowband electromagnetic radiation (previously called escaping nonthermal continuum radiation) is being generated. These observations show a direct correspondence between the narrowband radio emissions and electron cyclotron harmonic waves near the upper hybrid resonance frequency. In addition, electromagnetic radiation propagating in the Z-mode is observed in the source region which provides an extremely accurate determination of the electron plasma frequency and, hence, density profile of the source region. The data strongly suggest that electrostatic waves and not Cerenkov radiation are the source of the banded radio emissions and define the coupling which must be described by any viable theory.
Indirect detection of radiation sources through direct detection of radiolysis products
Farmer, Joseph C.; Fischer, Larry E.; Felter, Thomas E.
2010-04-20
A system for indirectly detecting a radiation source by directly detecting radiolytic products. The radiation source emits radiation and the radiation produces the radiolytic products. A fluid is positioned to receive the radiation from the radiation source. When the fluid is irradiated, radiolytic products are produced. By directly detecting the radiolytic products, the radiation source is detected.
Radicals and Non-Equilibrium Processes in Low-Temperature Plasmas
NASA Astrophysics Data System (ADS)
Petrović, Zoran; Mason, Nigel; Hamaguchi, Satoshi; Radmilović-Radjenović, Marija
2007-06-01
Serbian Academy of Sciences and Arts and Institute of Physics, Belgrade. Each Symposium has sought to highlight a key topic of plasma research and the 5th EU - Japan symposium explored the role of Radicals and Non-Equilibrium Processes in Low-Temperature Plasmas since these are key elements of plasma processing. Other aspects of technologies for manufacturing integrated circuits were also considered. Unlike bio-medicine and perhaps politics, in plasma processing free radicals are `good radicals' but their kinetics are difficult to understand since there remains little data on their collisions with electrons and ions. One of the goals of the symposium was to facilitate communication between experimentalists and theorists in binary collision physics with plasma modellers and practitioners of plasma processing in order to optimize efforts to provide much needed data for both molecules and radicals of practical importance. The non-equilibrium nature of plasmas is critical in the efficient manufacturing of high resolution structures by anisotropic plasma etching on Si wafers since they allow separate control of the directionality and energy of ions and provide a high level of separation between the mean energies of electrons and ions. As nanotechnologies become practical, plasma processing may play a key role, not only in manufacturing of integrated circuits, but also for self-organization of massively parallel manufacturing of nanostructures. In this Symposium the key issues that are hindering the development of such new, higher resolution technologies were discussed and some possible solutions were proposed. In particular, damage control, fast neutral etching, processes at surface and modeling of profiles were addressed in several of the lectures. A wide range of topics are covered in this book including atomic and molecular collision physics - primarily focused towards formation and analysis of radicals, basic swarm data and breakdown kinetics, basic kinetics of RF and DC
Transition undulator radiation as bright infrared sources
Kim, K.J.
1995-02-01
Undulator radiation contains, in addition to the usual component with narrow spectral features, a broad-band component in the low frequency region emitted in the near forward direction, peaked at an angle 1/{gamma}, where {gamma} is the relativistic factor. This component is referred to as the transition undulator radiation, as it is caused by the sudden change in the electron`s longitudinal velocity as it enters and leaves the undulator. The characteristic of the transition undulator radiation are analyzed and compared with the infrared radiation from the usual undulator harmonics and from bending magnets.
[UV-radiation--sources, wavelength, environment].
Hölzle, Erhard; Hönigsmann, Herbert
2005-09-01
The UV-radiation in our environment is part of the electromagnetic radiation, which emanates from the sun. It is designated as optical radiation and reaches from 290-4,000 nm on the earth's surface. According to international definitions UV irradiation is divided into short-wave UVC (200-280 nm), medium-wave UVB (280-320 nm), and long-wave UVA (320-400 nm). Solar radiation which reaches the surface of the globe at a defined geographical site and a defined time point is called global radiation. It is modified quantitatively and qualitatively while penetrating the atmosphere. Besides atmospheric conditions, like ozone layer and air pollution, geographic latitude, elevation, time of the season, time of the day, cloudiness and the influence of indirect radiation resulting from stray effects in the atmosphere and reflection from the underground play a role in modifying global radiation, which finally represents the biologically effective radiation. The radiation's distribution on the body surface varies according to sun angle and body posture. The cumulative UV exposure is mainly influenced by outdoor profession and recreational activities. The use of sun beds and phototherapeutic measures additionally may contribute to the cumulative UV dose.
Dotov, D G; Kim, S; Frank, T D
2015-02-01
We derive explicit expressions for the non-equilibrium thermodynamical variables of a canonical-dissipative limit cycle oscillator describing rhythmic motion patterns of active systems. These variables are statistical entropy, non-equilibrium internal energy, and non-equilibrium free energy. In particular, the expression for the non-equilibrium free energy is derived as a function of a suitable control parameter. The control parameter determines the Hopf bifurcation point of the deterministic active system and describes the effective pumping of the oscillator. In analogy to the equilibrium free energy of the Landau theory, it is shown that the non-equilibrium free energy decays as a function of the control parameter. In doing so, a similarity between certain equilibrium and non-equilibrium phase transitions is pointed out. Data from an experiment on human rhythmic movements is presented. Estimates for pumping intensity as well as the thermodynamical variables are reported. It is shown that in the experiment the non-equilibrium free energy decayed when pumping intensity was increased, which is consistent with the theory. Moreover, pumping intensities close to zero could be observed at relatively slow intended rhythmic movements. In view of the Hopf bifurcation underlying the limit cycle oscillator model, this observation suggests that the intended limit cycle movements were actually more similar to trajectories of a randomly perturbed stable focus.
Dotov, D G; Kim, S; Frank, T D
2015-02-01
We derive explicit expressions for the non-equilibrium thermodynamical variables of a canonical-dissipative limit cycle oscillator describing rhythmic motion patterns of active systems. These variables are statistical entropy, non-equilibrium internal energy, and non-equilibrium free energy. In particular, the expression for the non-equilibrium free energy is derived as a function of a suitable control parameter. The control parameter determines the Hopf bifurcation point of the deterministic active system and describes the effective pumping of the oscillator. In analogy to the equilibrium free energy of the Landau theory, it is shown that the non-equilibrium free energy decays as a function of the control parameter. In doing so, a similarity between certain equilibrium and non-equilibrium phase transitions is pointed out. Data from an experiment on human rhythmic movements is presented. Estimates for pumping intensity as well as the thermodynamical variables are reported. It is shown that in the experiment the non-equilibrium free energy decayed when pumping intensity was increased, which is consistent with the theory. Moreover, pumping intensities close to zero could be observed at relatively slow intended rhythmic movements. In view of the Hopf bifurcation underlying the limit cycle oscillator model, this observation suggests that the intended limit cycle movements were actually more similar to trajectories of a randomly perturbed stable focus. PMID:25619737
Improved source of infrared radiation for spectroscopy
NASA Technical Reports Server (NTRS)
Burkhard, D. G.; Rao, K. N.
1971-01-01
Radiation from a crimped V-groove in the electrically heated metallic element of a high-resolution infrared spectrometer is more intense than that from plane areas adjacent to the element. Radiation from the vee and the flat was compared by alternately focusing on the entrance slit of a spectrograph.
Large area radiation source for water and wastewater treatment
NASA Astrophysics Data System (ADS)
Mueller, Michael T.; Lee, Seungwoo; Kloba, Anthony; Hellmer, Ronald; Kumar, Nalin; Eaton, Mark; Rambo, Charlotte; Pillai, Suresh
2011-06-01
There is a strong desire for processes that improve the safety of water supplies and that minimize disinfection byproducts. Stellarray is developing mercury-free next-generation x-ray and UV-C radiation sources in flat-panel and pipe form factors for water and wastewater treatment applications. These new radiation sources are designed to sterilize sludge and effluent, and to enable new treatment approaches to emerging environmental concerns such as the accumulation of estrogenic compounds in water. Our UV-C source, based on cathodoluminescent technology, differs significantly from traditional disinfection approaches using mercury arc lamps or UV LEDs. Our sources accelerate electrons across a vacuum gap, converting their energy into UV-C when striking a phosphor, or x-rays when striking a metallic anode target. Stellarray's large area radiation sources for wastewater treatment allow matching of the radiation source area to the sterilization target area for maximum coverage and improved efficiency.
Radiation Protection for Manned Interplanetary Missions - Radiation Sources, Risks, Remedies
NASA Astrophysics Data System (ADS)
Facius, R.; Reitz, G.
Health risks in interplanetary explorative missions differ in two major features significantly from those during the manned missions experienced so far. For one, presently available technologies lead to durations of such missions significantly longer than so far encountered - with the added complication that emergency returns are ruled out. Thus radiation exposures and hence risks for late radiation sequelae like cancer increase proportional to mission duration - similar like most other health and many technical risks too. Secondly, loss of the geomagnetic shielding available in low earth orbits (LEO) does increase the radiation dose rates from galactic cosmic rays (GCR) since significant fractions of the GCR flux below about 10 GeV/n now can reach the space vehicle. In addition, radiation from solar particle events (SPE) which at most in polar orbit segments can contribute to the radiation exposure during LEO missions now can reach the spaceship unattenuated. Radiation doses from extreme SPEs can reach levels where even early acute radiation sickness might ensue - with the added risks from potentially associated crew performance decrements. In contrast to the by and large predictable GCR contribution, the doses and hence risks from large SPEs can only stochastically be assessed. Mission designers face the task to contain the overall health risk within acceptable limits. Towards this end they have to transport the particle fluxes of the radiation fields in free space through the walls of the spaceship and through the tissue of the astronaut to the radiation sensitive organs. To obtain a quantity which is useful for risk assessment, the radiobiological effectiveness as well as the specific sensitivity of a given organ has to be accounted for in such transport calculations which of course require a detailed knowledge of the spatial distribution and the atomic composition of the surrounding shielding material. In doing so the mission designer encounters two major
Mac Low, Mordecai-Mark; Glover, Simon C. O. E-mail: glover@uni-heidelberg.de
2012-02-20
Observations of spiral galaxies show a strong linear correlation between the ratio of molecular to atomic hydrogen surface density R{sub mol} and midplane pressure. To explain this, we simulate three-dimensional, magnetized turbulence, including simplified treatments of non-equilibrium chemistry and the propagation of dissociating radiation, to follow the formation of H{sub 2} from cold atomic gas. The formation timescale for H{sub 2} is sufficiently long that equilibrium is not reached within the 20-30 Myr lifetimes of molecular clouds. The equilibrium balance between radiative dissociation and H{sub 2} formation on dust grains fails to predict the time-dependent molecular fractions we find. A simple, time-dependent model of H{sub 2} formation can reproduce the gross behavior, although turbulent density perturbations increase molecular fractions by a factor of few above it. In contradiction to equilibrium models, radiative dissociation of molecules plays little role in our model for diffuse radiation fields with strengths less than 10 times that of the solar neighborhood, because of the effective self-shielding of H{sub 2}. The observed correlation of R{sub mol} with pressure corresponds to a correlation with local gas density if the effective temperature in the cold neutral medium of galactic disks is roughly constant. We indeed find such a correlation of R{sub mol} with density. If we examine the value of R{sub mol} in our local models after a free-fall time at their average density, as expected for models of molecular cloud formation by large-scale gravitational instability, our models reproduce the observed correlation over more than an order-of-magnitude range in density.
Non-equilibrium Green's functions study of discrete dopants variability on an ultra-scaled FinFET
Valin, R. Martinez, A.; Barker, J. R.
2015-04-28
In this paper, we study the effect of random discrete dopants on the performance of a 6.6 nm channel length silicon FinFET. The discrete dopants have been distributed randomly in the source/drain region of the device. Due to the small dimensions of the FinFET, a quantum transport formalism based on the non-equilibrium Green's functions has been deployed. The transfer characteristics for several devices that differ in location and number of dopants have been calculated. Our results demonstrate that discrete dopants modify the effective channel length and the height of the source/drain barrier, consequently changing the channel control of the charge. This effect becomes more significant at high drain bias. As a consequence, there is a strong effect on the variability of the on-current, off-current, sub-threshold slope, and threshold voltage. Finally, we have also calculated the mean and standard deviation of these parameters to quantify their variability. The obtained results show that the variability at high drain bias is 1.75 larger than at low drain bias. However, the variability of the on-current, off-current, and sub-threshold slope remains independent of the drain bias. In addition, we have found that a large source to drain current by tunnelling current occurs at low gate bias.
NASA Astrophysics Data System (ADS)
Ozawa, H.; Shimokawa, S.
2005-12-01
Regular pattern formation in a nonlinear non-equilibrium system is investigated from an energetic viewpoint. A nonlinear system is driven by available energy (energy available for conversion to kinetic energy) supplied from its non-equilibrium surroundings, and this energy is dissipated through small-scale dissipation processes in the system (i.e., entropy production). A power balance equation is formulated for the change rate of the total available energy of a system: C = G - D, where G is the generation rate of the available energy and D is the dissipation rate due to thermal and viscous dissipation (entropy production). The change rate C is zero when the concerned system is in a steady state, whereas it is positive (acceleration) or negative (deceleration) in non-steady transitional periods. A fluctuation in a macroscopic physical variable, such as fluid velocity, can change the value G, while it does not change the value D immediately when the scale of the fluctuation is larger than the dissipation scale. The large-scale fluctuation that increases G can therefore grow by the positive gain in the available energy (C > 0) through a nonlinear feedback process. This feedback process can thus drive the system towards a state with the maximum G, which also corresponds to the maximum D in the steady state (C = 0). It follows from mathematical manipulation that the change rate C is proportional to the decrease rate of entropy of a concerned system - the system's entropy must decrease during the acceleration period (C > 0). This result is consistent with our observations that regular patterns or orderly structures emerge spontaneously in the developing stages of the nonlinear non-equilibrium systems. Some examples (e.g., Benard convection, ocean circulation and granular pattern formation) are discussed in this respect.
Non-equilibrium thermodynamics, maximum entropy production and Earth-system evolution.
Kleidon, Axel
2010-01-13
The present-day atmosphere is in a unique state far from thermodynamic equilibrium. This uniqueness is for instance reflected in the high concentration of molecular oxygen and the low relative humidity in the atmosphere. Given that the concentration of atmospheric oxygen has likely increased throughout Earth-system history, we can ask whether this trend can be generalized to a trend of Earth-system evolution that is directed away from thermodynamic equilibrium, why we would expect such a trend to take place and what it would imply for Earth-system evolution as a whole. The justification for such a trend could be found in the proposed general principle of maximum entropy production (MEP), which states that non-equilibrium thermodynamic systems maintain steady states at which entropy production is maximized. Here, I justify and demonstrate this application of MEP to the Earth at the planetary scale. I first describe the non-equilibrium thermodynamic nature of Earth-system processes and distinguish processes that drive the system's state away from equilibrium from those that are directed towards equilibrium. I formulate the interactions among these processes from a thermodynamic perspective and then connect them to a holistic view of the planetary thermodynamic state of the Earth system. In conclusion, non-equilibrium thermodynamics and MEP have the potential to provide a simple and holistic theory of Earth-system functioning. This theory can be used to derive overall evolutionary trends of the Earth's past, identify the role that life plays in driving thermodynamic states far from equilibrium, identify habitability in other planetary environments and evaluate human impacts on Earth-system functioning.
Gas-Liquid Interfacial Non-Equilibrium Plasmas for Structure Controlled Nanoparticles
NASA Astrophysics Data System (ADS)
Kaneko, Toshiro
2013-10-01
Plasmas generated in liquid or in contact with liquid have attracted much attention as a novel reactive field in the nano-bio material creation because the brand-new chemical and biological reactions are yielded at the gas-liquid interface, which are induced by the physical actions of the non-equilibrium plasmas. In this study, first, size- and structure-controlled gold nanoparticles (AuNPs) covered with DNA are synthesized using a pulse-driven gas-liquid interfacial discharge plasma (GLIDP) for the application to next-generation drug delivery systems. The size and assembly of the AuNPs are found to be easily controlled by changing the plasma parameters and DNA concentration in the liquid. On the other hand, the mono-dispersed, small-sized, and interval-controlled AuNPs are synthesized by using the carbon nanotubes (CNTs) as a template, where the CNTs are functionalized by the ion and radical irradiation in non-equilibrium plasmas. These new materials are now widely applied to the solar cell, optical devices, and so on. Second, highly-ordered periodic structures of the AuNPs are formed by transcribing the periodic plasma structure to the surface of the liquid, where the spatially selective synthesis of the AuNPs is realized. This phenomenon is well explained by the reduction and oxidation effects of the radicals which are generated by the non-equilibrium plasma irradiation to the liquid and resultant dissociation of the liquid. In addition, it is attempted to form nano- or micro-scale periodic structures of the AuNPs based on the self-organizing behavior of turbulent plasmas generated by the nonlinear development of plasma fluctuations at the gas-liquid interface.
Radiation sources and diagnostics with ultrashort electron bunches
Catravas, P.; Esarey, E.; Leemans, W.P.
2001-11-02
The basic principles and design of radiation sources (transition radiation, Cerenkov radiation, radiation from periodic structures, etc.) and radiation-based diagnostics will be discussed, with emphasis on radiation from ultra-short electron bunches. Ultra-short electron bunches have the potential to produce high peak flux radiation sources that cover wavelength regimes where sources are currently not widely available (coherent THz/IR) as well as ultrashort X-ray pulses (3-100 fs). While radiation from the electron bunch contains the full signature of the electron beam and/or medium it has travelled through, the deconvolution of a single property of interest can be difficult due to a large number of contributing properties. The experimental implementation of novel solutions to this problem will be described for beams from 30 MeV to 30 GeV, including fluctuational interferometry, source imaging, phase matched cone angles and laser-based techniques, which utilize optical transition radiation, wiggler and Cerenkov radiation, and Thomson scattering. These novel diagnostic methods have the potential to resolve fs bunch durations, slice emittance on fs scales, etc. The advantages and novel features of these techniques will be discussed.
Non-equilibrium electron transport in degenerate nitride heterostructures-dynamic screening effects
NASA Astrophysics Data System (ADS)
Anderson, D. R.; Babiker, M.; Bennett, C. R.; Probert, M. I. J.
2003-04-01
We show how dynamic screening effects on non-equilibrium electron transport can be incorporated in the case of electronically dense GaN-based quantum wells. The theory is based on the Boltzmann equation, leading to evaluations of the momentum relaxation time and, hence, the electron mobility in these heterostructures. We find that both screening and anti-screening effects are manifest as the electron density varies. However, anti-screening dominates over a wide range of densities, with screening commencing at densities appropriate for phonon-plasmon coupling.
Vibrational non-equilibrium in the hydrogen-oxygen reaction. Comparison with experiment
NASA Astrophysics Data System (ADS)
Skrebkov, Oleg V.
2015-03-01
A theoretical model is proposed for the chemical and vibrational kinetics of hydrogen oxidation based on consistent accounting of the vibrational non-equilibrium of the HO2 radical that forms as a result of the bimolecular recombination H+O2 → HO2. In the proposed model, the chain branching H+O2 = O+OH and inhibiting H+O2+M = HO2+M formal reactions are treated (in the terms of elementary processes) as a single multi-channel process of forming, intramolecular energy redistribution between modes, relaxation, and unimolecular decay of the comparatively long-lived vibrationally excited HO2 radical, which is able to react and exchange energy with the other components of the mixture. The model takes into account the vibrational non-equilibrium of the starting (primary) H2 and O2 molecules, as well as the most important molecular intermediates HO2, OH, O2(1Δ), and the main reaction product H2O. It is shown that the hydrogen-oxygen reaction proceeds in the absence of vibrational equilibrium, and the vibrationally excited HO2(v) radical acts as a key intermediate in a fundamentally important chain branching process and in the generation of electronically excited species O2(1Δ), O(1D), and OH(2Σ+). The calculated results are compared with the shock tube experimental data for strongly diluted H2-O2 mixtures at 1000 < T < 2500 K, 0.5 < p < 4 atm. It is demonstrated that this approach is promising from the standpoint of reconciling the predictions of the theoretical model with experimental data obtained by different authors for various compositions and conditions using different methods. For T < 1500 K, the nature of the hydrogen-oxygen reaction is especially non-equilibrium, and the vibrational non-equilibrium of the HO2 radical is the essence of this process. The quantitative estimation of the vibrational relaxation characteristic time of the HO2 radical in its collisions with H2 molecules has been obtained as a result of the comparison of different experimental data on
Evolution of non-equilibrium entanglement networks in spincast thin polymer films
NASA Astrophysics Data System (ADS)
Dalnoki-Veress, Kari; McGraw, Joshua; Fowler, Paul
2012-02-01
Measuring the rheology of non-equilibrium thin polymer films has received significant attention recently. Experiments are typically performed on thin polymer films that inherit their structure from spin coating. While the results of several rheological experiments paint a clear picture, details of molecular configurations in spincast polymer films are still unknown. Here we present the results of crazing measurements which demonstrate that the effective entanglement density of thin polymer films changes as a function of annealing toward a stable equilibrium value. The effective entanglement density plateaus with a time scale on the same order as the bulk reptation time.
Equilibrium state and non-equilibrium steady state in an isolated human system
NASA Astrophysics Data System (ADS)
Zheng, Wen-Zhi; Liang, Yuan; Huang, Ji-Ping
2014-02-01
The principle of increasing entropy (PIE) is commonly considered as a universal physical law for natural systems. It also means that a non-equilibrium steady state (NESS) must not appear in any isolated natural systems. Here we experimentally investigate an isolated human social system with a clustering effect. We report that the PIE cannot always hold, and that NESSs can come to appear. Our study highlights the role of human adaptability in the PIE, and makes it possible to study human social systems by using some laws originating from traditional physics.
Non-equilibrium Dynamics in Zeeman-Limited Superconducting Al Films
NASA Astrophysics Data System (ADS)
Prestigiacomo, J. C.; Adams, P. W.
2016-05-01
We report non-equilibrium dynamics in the tunneling density of states of ultra-thin Al films in high Zeeman fields. We have measured the transport and tunneling density of states of the films through the first-order Zeeman critical field transition. Films with sheet resistances of a few hundred ohms exhibit slow, non-exponential relaxation in the hysteretic critical field region. The relaxation traces are interspersed with abrupt avalanche-like collapses of the condensate on the superheating branch of the critical field hysteresis loop but not on the supercooling branch. We believe that film dynamics reflects an inhomogeneous order parameter that emerges in the critical field region.
Synthesis of silane and silicon in a non-equilibrium plasma jet
NASA Technical Reports Server (NTRS)
Calcote, H. F.; Felder, W.
1977-01-01
The feasibility of using a non-equilibrium hydrogen plasma jet as a chemical synthesis tool was investigated. Four possible processes were identified for further study: (1) production of polycrystalline silicon photovoltaic surfaces, (2) production of SiHCl3 from SiCl4, (3) production of SiH4 from SiHCl3, and (4) purification of SiCl4 by metal impurity nucleation. The most striking result was the recognition that the strongly adhering silicon films, amorphous or polycrystalline, produced in our studies could be the basis for preparing a photovoltaic surface directly; this process has potential advantages over other vapor deposition processes.
NASA Astrophysics Data System (ADS)
Shiraishi, Hiroyuki
2015-09-01
Microwave-supported Detonation (MSD), one type of Microwave-supported Plasma (MSP), is considered as one of the most important phenomena because it can generate high pressure and high temperature for beam-powered space propulsion systems. In this study, I numerically simulate MSD waves propagating through a diatomic gas. In order to evaluate the threshold of beam intensity, I use the physical-fluid dynamics scheme, which has been developed for simulating unsteady and non-equilibrium LSD waves propagating through a hydrogen gas.
Non-equilibrium slave bosons approach to quantum pumping in interacting quantum dots
NASA Astrophysics Data System (ADS)
Citro, Roberta; Romeo, Francesco
2016-03-01
We review a time-dependent slave bosons approach within the non-equilibrium Green's function technique to analyze the charge and spin pumping in a strongly interacting quantum dot. We study the pumped current as a function of the pumping phase and of the dot energy level and show that a parasitic current arises, beyond the pure pumping one, as an effect of the dynamical constraints. We finally illustrate an all-electrical mean for spin-pumping and discuss its relevance for spintronics applications.
Source of coherent short wavelength radiation
Villa, Francesco
1990-01-01
An apparatus for producing coherent radiation ranging from X-rays to the far ultraviolet (i.e., 1 Kev to 10 eV) utilizing the Compton scattering effect. A photon beam from a laser is scattered on a high energy electron bunch from a pulse power linac. The short wavelength radiation produced by such scattering has sufficient intensity and spatial coherence for use in high resolution applications such as microscopy.
Cooper, F.
1997-09-22
This paper contains viewgraphs on unusual dileptons at Brookhaven RHIC. A field theory approach is used based on a non-equilibrium chiral phase transformation utilizing the schroedinger and Heisenberg picture.
Wu, Wei; Wang, Jin
2013-09-28
We established a potential and flux field landscape theory to quantify the global stability and dynamics of general spatially dependent non-equilibrium deterministic and stochastic systems. We extended our potential and flux landscape theory for spatially independent non-equilibrium stochastic systems described by Fokker-Planck equations to spatially dependent stochastic systems governed by general functional Fokker-Planck equations as well as functional Kramers-Moyal equations derived from master equations. Our general theory is applied to reaction-diffusion systems. For equilibrium spatially dependent systems with detailed balance, the potential field landscape alone, defined in terms of the steady state probability distribution functional, determines the global stability and dynamics of the system. The global stability of the system is closely related to the topography of the potential field landscape in terms of the basins of attraction and barrier heights in the field configuration state space. The effective driving force of the system is generated by the functional gradient of the potential field alone. For non-equilibrium spatially dependent systems, the curl probability flux field is indispensable in breaking detailed balance and creating non-equilibrium condition for the system. A complete characterization of the non-equilibrium dynamics of the spatially dependent system requires both the potential field and the curl probability flux field. While the non-equilibrium potential field landscape attracts the system down along the functional gradient similar to an electron moving in an electric field, the non-equilibrium flux field drives the system in a curly way similar to an electron moving in a magnetic field. In the small fluctuation limit, the intrinsic potential field as the small fluctuation limit of the potential field for spatially dependent non-equilibrium systems, which is closely related to the steady state probability distribution functional, is
Resonance microwave discharge as a source of UV radiation
Barkhudarov, E. M.; Denisova, N. V.; Kossyi, I. A.; Misakyan, M. A.
2009-07-15
Results are presented from theoretical and experimental studies of an optical radiation source based on a microwave discharge excited in an Ar + Hg mixture. The main attention is paid to the so-called 'resonance' discharge operating at low pressures of the working gas (argon). It is shown that a decrease in the Ar pressure leads to significant increase in the Hg radiation intensity (including biologically active UV radiation) and considerable decrease in the intensity of argon emission lines. The intensity of discharge radiation is calculated in the framework of the collisional-radiative model. The results of calculation agree qualitatively with experimental data.
Okazaki, Yasumasa; Wang, Yue; Tanaka, Hiromasa; Mizuno, Masaaki; Nakamura, Kae; Kajiyama, Hiroaki; Kano, Hiroyuki; Uchida, Koji; Kikkawa, Fumitaka; Hori, Masaru; Toyokuni, Shinya
2014-01-01
Thermal plasmas and lasers are used in medicine to cut and ablate tissues and for coagulation. Non-equilibrium atmospheric pressure plasma (NEAPP) is a recently developed, non-thermal technique with possible biomedical applications. Although NEAPP reportedly generates reactive oxygen/nitrogen species, electrons, positive ions, and ultraviolet radiation, little research has been done into the use of this technique for conventional free radical biology. Recently, we developed a NEAPP device with high electron density. Electron spin resonance spin-trapping revealed •OH as a major product. To obtain evidence of NEAPP-induced oxidative modifications in biomolecules and standardize them, we evaluated lipid peroxidation and DNA modifications in various in vitro and ex vivo experiments. Conjugated dienes increased after exposure to linoleic and α-linolenic acids. An increase in 2-thiobarbituric acid-reactive substances was also observed after exposure to phosphatidylcholine, liposomes or liver homogenate. Direct exposure to rat liver in saline produced immunohistochemical evidence of 4-hydroxy-2-nonenal- and acrolein-modified proteins. Exposure to plasmid DNA induced dose-dependent single/double strand breaks and increased the amounts of 8-hydroxy-2'-deoxyguanosine and cyclobutane pyrimidine dimers. These results indicate that oxidative biomolecular damage by NEAPP is dose-dependent and thus can be controlled in a site-specific manner. Simultaneous oxidative and UV-specific DNA damage may be useful in cancer treatment. PMID:25411528
Laser induced plasma on copper target, a non-equilibrium model
Oumeziane, Amina Ait Liani, Bachir; Parisse, Jean-Denis
2014-02-15
The aim of this work is to present a comprehensive numerical model for the UV laser ablation of metal targets, it focuses mainly on the prediction of laser induced plasma thresholds, the effect of the laser-plasma interaction, and the importance of the electronic non-equilibrium in the laser induced plume and its expansion in the background gas. This paper describes a set of numerical models for laser-matter interaction between 193-248 and 355 nm lasers and a copper target. Along with the thermal effects inside the material resulting from the irradiation of the latter with the pulsed laser, the laser-evaporated matter interaction and the plasma formation are thoroughly modelled. In the laser induced plume, the electronic nonequilibrium and the laser beam absorption have been investigated. Our calculations of the plasmas ignition thresholds on copper targets have been validated and compared to experimental as well as theoretical results. Comparison with experiment data indicates that our results are in good agreement with those reported in the literature. Furthermore, the inclusion of electronic non-equilibrium in our work indicated that this important process must be included in models of laser ablation and plasma plume formation.
Non-equilibrium dynamics and floral trait interactions shape extant angiosperm diversity
O'Meara, Brian C.; Smith, Stacey D.; Armbruster, W. Scott; Harder, Lawrence D.; Hardy, Christopher R.; Hileman, Lena C.; Hufford, Larry; Litt, Amy; Magallón, Susana; Smith, Stephen A.; Stevens, Peter F.; Fenster, Charles B.; Diggle, Pamela K.
2016-01-01
Why are some traits and trait combinations exceptionally common across the tree of life, whereas others are vanishingly rare? The distribution of trait diversity across a clade at any time depends on the ancestral state of the clade, the rate at which new phenotypes evolve, the differences in speciation and extinction rates across lineages, and whether an equilibrium has been reached. Here we examine the role of transition rates, differential diversification (speciation minus extinction) and non-equilibrium dynamics on the evolutionary history of angiosperms, a clade well known for the abundance of some trait combinations and the rarity of others. Our analysis reveals that three character states (corolla present, bilateral symmetry, reduced stamen number) act synergistically as a key innovation, doubling diversification rates for lineages in which this combination occurs. However, this combination is currently less common than predicted at equilibrium because the individual characters evolve infrequently. Simulations suggest that angiosperms will remain far from the equilibrium frequencies of character states well into the future. Such non-equilibrium dynamics may be common when major innovations evolve rarely, allowing lineages with ancestral forms to persist, and even outnumber those with diversification-enhancing states, for tens of millions of years. PMID:27147092
Non-equilibrium depletion interactions: first things attract, then they repel
NASA Astrophysics Data System (ADS)
Dolata, Benjamin; Zia, Roseanna
2015-11-01
Non-Equilibrium depletion interactions in colloidal dispersions are studied theoretically via a combination of asymptotic and numerical solutions of the Smoluchowski equation. A pair of probes at arbitrary separation is driven by an external force at arbitrary orientation through a suspension, deforming the surrounding microstructure. The degree to which the structure is distorted, and the shape of this deformation, depends on the separation between the probes, on the orientation of the pair to the driving force, and on the strength with which the probes are forced relative to the entropic restoring force of the suspension particles. The resultant non-equilibrium osmotic pressure gradients give rise to both drag and interactive forces between the probes. When the external force is zero, the depletion attraction of Asakura and Oosawa is recovered. When an external force is applied, the interactive force can lead either to attraction or repulsion, as well as deterministic re-orientation of the probes relative to the external force, depending on initial separation, orientation, and strength of forcing. The use of this model for interrogation of non-continuum and elastically networked materials is explored.
Chen, Yunjie; Roux, Benoît
2015-01-14
A family of hybrid simulation methods that combines the advantages of Monte Carlo (MC) with the strengths of classical molecular dynamics (MD) consists in carrying out short non-equilibrium MD (neMD) trajectories to generate new configurations that are subsequently accepted or rejected via an MC process. In the simplest case where a deterministic dynamic propagator is used to generate the neMD trajectories, the familiar Metropolis acceptance criterion based on the change in the total energy ΔE, min[1, exp( − βΔE)], guarantees that the hybrid algorithm will yield the equilibrium Boltzmann distribution. However, the functional form of the acceptance probability is more complex when the non-equilibrium switching process is generated via a non-deterministic stochastic dissipative propagator coupled to a heat bath. Here, we clarify the conditions under which the Metropolis criterion remains valid to rigorously yield a proper equilibrium Boltzmann distribution within hybrid neMD-MC algorithm.
Long-lived non-equilibrium states in a quantum-Hall Tomonaga-Luttinger liquid
NASA Astrophysics Data System (ADS)
Fujisawa, Toshimasa; Washio, Kazuhisa; Nakazawa, Ryo; Hashisaka, Masayuki; Muraki, Koji; Tokura, Yasuhiro
The existence of long-lived non-equilibrium states without showing thermalization, which has previously been demonstrated in time evolution of ultracold atoms (quantum quench), suggests the possibility of their spatial analogue in transport behavior of interacting electrons in solid-state systems. Here we report long-lived non-equilibrium states in one-dimensional edge channels in the integer quantum Hall regime. For this purpose, non-trivial binary spectrum composed of hot and cold carriers is prepared by an indirect heating scheme using weakly coupled counterpropagating edge channels in an AlGaAs/GaAs heterostructure. Quantum dot spectroscopy clearly reveals that the carriers with the non-trivial binary spectrum propagate over a long distance (5 - 10 um), much longer than the length required for electronic relaxation (about 0.1 um), without thermalization into a trivial Fermi distribution. This observation is consistent with the integrable model of Tomonaga-Luttinger liquid. The long-lived spectrum implies that the system is well described by non-interacting plasmons, which are attractive for carrying information for a long distance. This work was supported by the JSPS 26247051 and 15H05854, and Nanotechnology Platform Program of MEXT.
A tightly coupled non-equilibrium model for inductively coupled radio-frequency plasmas
NASA Astrophysics Data System (ADS)
Munafò, A.; Alfuhaid, S. A.; Cambier, J.-L.; Panesi, M.
2015-10-01
The objective of the present work is the development of a tightly coupled magneto-hydrodynamic model for inductively coupled radio-frequency plasmas. Non Local Thermodynamic Equilibrium (NLTE) effects are described based on a hybrid State-to-State approach. A multi-temperature formulation is used to account for thermal non-equilibrium between translation of heavy-particles and vibration of molecules. Excited electronic states of atoms are instead treated as separate pseudo-species, allowing for non-Boltzmann distributions of their populations. Free-electrons are assumed Maxwellian at their own temperature. The governing equations for the electro-magnetic field and the gas properties (e.g., chemical composition and temperatures) are written as a coupled system of time-dependent conservation laws. Steady-state solutions are obtained by means of an implicit Finite Volume method. The results obtained in both LTE and NLTE conditions over a broad spectrum of operating conditions demonstrate the robustness of the proposed coupled numerical method. The analysis of chemical composition and temperature distributions along the torch radius shows that: (i) the use of the LTE assumption may lead to an inaccurate prediction of the thermo-chemical state of the gas, and (ii) non-equilibrium phenomena play a significant role close the walls, due to the combined effects of Ohmic heating and macroscopic gradients.
Non-equilibrium fluid flow around the Yucca Mountain Nuclear Waste Repository
Reis, J.C.
1995-08-01
The results of this study are consistent with the G-Tunnel test results, which indicated no water bank forming above the dry zone, and differ from the simulation results based on the equivalent continuum model (ECM), which indicated a water bank may form above the dry zone. The reason that the simulation studies predict the creation of a water bank is that the ECM assumes capillary equilibrium between the fractures and matrix. This study quantified the non-equilibrium fluid flow between the fractures and matrix and has shown that water entering the fractures above the dry zone will drain away from the repository before capillary equilibrium could be created. Thus, the ECM models are inappropriate for many studies of water transport around the proposed Yucca Mountain repository. It is noted that the authors of the ECM studies recognized this limitation and recommended that the more difficult non-equilibrium studies be conducted. It is concluded that a significant water bank above the repository from the redistribution of water from nuclear decay heating is unlikely. Thus, the integrity of the repository is not expected to-be threatened by rewetting of the formation from a water bank.
Phase-field investigation on the non-equilibrium interface dynamics of rapid alloy solidification
Choi, Jeong
2011-01-01
The research program reported here is focused on critical issues that represent conspicuous gaps in current understanding of rapid solidification, limiting our ability to predict and control microstructural evolution (i.e. morphological dynamics and microsegregation) at high undercooling, where conditions depart significantly from local equilibrium. More specifically, through careful application of phase-field modeling, using appropriate thin-interface and anti-trapping corrections and addressing important details such as transient effects and a velocity-dependent (i.e. adaptive) numerics, the current analysis provides a reasonable simulation-based picture of non-equilibrium solute partitioning and the corresponding oscillatory dynamics associated with single-phase rapid solidification and show that this method is a suitable means for a self-consistent simulation of transient behavior and operating point selection under rapid growth conditions. Moving beyond the limitations of conventional theoretical/analytical treatments of non-equilibrium solute partitioning, these results serve to substantiate recent experimental findings and analytical treatments for single-phase rapid solidification. The departure from the equilibrium solid concentration at the solid-liquid interface was often observed during rapid solidification, and the energetic associated non-equilibrium solute partitioning has been treated in detail, providing possible ranges of interface concentrations for a given growth condition. Use of these treatments for analytical description of specific single-phase dendritic and cellular operating point selection, however, requires a model for solute partitioning under a given set of growth conditions. Therefore, analytical solute trapping models which describe the chemical partitioning as a function of steady state interface velocities have been developed and widely utilized in most of the theoretical investigations of rapid solidification. However, these
Giant THz photoconductivity and possible non-equilibrium superconductivity in metallic K3C60
Mitrano, M.; Cantaluppi, A.; Nicoletti, D.; Kaiser, S.; Perucchi, A.; Lupi, S.; Di Pietro, P.; Pontiroli, D.; Riccò, M.; Clark, S. R.; Jaksch, D.; Cavalleri, A.
2015-01-01
The non-equilibrium control of emergent phenomena in solids is an important research frontier, encompassing effects like the optical enhancement of superconductivity 1 . Recently, nonlinear excitation 2 , 3 of certain phonons in bilayer cuprates was shown to induce superconducting-like optical properties at temperatures far above Tc 4,5,6. This effect was accompanied by the disruption of competing charge-density-wave correlations7,8, which explained some but not all of the experimental results. Here, we report a similar phenomenon in a very different compound. By exciting metallic K3C60 with mid-infrared optical pulses, we induce a large increase in carrier mobility, accompanied by the opening of a gap in the optical conductivity. Strikingly, these same signatures are observed at equilibrium when cooling metallic K3C60 below the superconducting transition temperature (Tc = 20 K). Although optical techniques alone cannot unequivocally identify non-equilibrium high-temperature superconductivity, we propose this scenario as a possible explanation of our results. PMID:26855424
Non-equilibrium dynamics and floral trait interactions shape extant angiosperm diversity.
O'Meara, Brian C; Smith, Stacey D; Armbruster, W Scott; Harder, Lawrence D; Hardy, Christopher R; Hileman, Lena C; Hufford, Larry; Litt, Amy; Magallón, Susana; Smith, Stephen A; Stevens, Peter F; Fenster, Charles B; Diggle, Pamela K
2016-05-11
Why are some traits and trait combinations exceptionally common across the tree of life, whereas others are vanishingly rare? The distribution of trait diversity across a clade at any time depends on the ancestral state of the clade, the rate at which new phenotypes evolve, the differences in speciation and extinction rates across lineages, and whether an equilibrium has been reached. Here we examine the role of transition rates, differential diversification (speciation minus extinction) and non-equilibrium dynamics on the evolutionary history of angiosperms, a clade well known for the abundance of some trait combinations and the rarity of others. Our analysis reveals that three character states (corolla present, bilateral symmetry, reduced stamen number) act synergistically as a key innovation, doubling diversification rates for lineages in which this combination occurs. However, this combination is currently less common than predicted at equilibrium because the individual characters evolve infrequently. Simulations suggest that angiosperms will remain far from the equilibrium frequencies of character states well into the future. Such non-equilibrium dynamics may be common when major innovations evolve rarely, allowing lineages with ancestral forms to persist, and even outnumber those with diversification-enhancing states, for tens of millions of years.
Non-equilibrium entropy and dynamics in a system with long-range interactions
NASA Astrophysics Data System (ADS)
Rocha Filho, T. M.
2016-05-01
We extend the core-halo approach of Levin et al (2014 Phys. Rep. 535, 1) for the violent relaxation of long-range interacting system with a waterbag initial condition, in the case of a widely studied Hamiltonian mean field model. The Gibbs entropy maximization principle is considered with the constraints of energy conservation and of coarse-grained Casimir invariants of the Vlasov equation. The core-halo distribution function depends only on the one-particle mean-field energy, as is expected from the Jeans theorem, and depends on a set of parameters which in our approach is completely determined without having to solve an envelope equation for the contour of the initial state, as required in the original approach. We also show that a different ansatz can be used for the core-halo distribution with similar results. This work also reveals a link between a parametric resonance causing the non-equilibrium phase transition in the model, a dynamical property, and a discontinuity of the (non-equilibrium) entropy of the system.
A tightly coupled non-equilibrium model for inductively coupled radio-frequency plasmas
Munafò, A. Alfuhaid, S. A. Panesi, M.; Cambier, J.-L.
2015-10-07
The objective of the present work is the development of a tightly coupled magneto-hydrodynamic model for inductively coupled radio-frequency plasmas. Non Local Thermodynamic Equilibrium (NLTE) effects are described based on a hybrid State-to-State approach. A multi-temperature formulation is used to account for thermal non-equilibrium between translation of heavy-particles and vibration of molecules. Excited electronic states of atoms are instead treated as separate pseudo-species, allowing for non-Boltzmann distributions of their populations. Free-electrons are assumed Maxwellian at their own temperature. The governing equations for the electro-magnetic field and the gas properties (e.g., chemical composition and temperatures) are written as a coupled system of time-dependent conservation laws. Steady-state solutions are obtained by means of an implicit Finite Volume method. The results obtained in both LTE and NLTE conditions over a broad spectrum of operating conditions demonstrate the robustness of the proposed coupled numerical method. The analysis of chemical composition and temperature distributions along the torch radius shows that: (i) the use of the LTE assumption may lead to an inaccurate prediction of the thermo-chemical state of the gas, and (ii) non-equilibrium phenomena play a significant role close the walls, due to the combined effects of Ohmic heating and macroscopic gradients.
An improved dynamic non-equilibrium wall-model for large eddy simulation
NASA Astrophysics Data System (ADS)
Park, George Ilhwan; Moin, Parviz
2014-01-01
A non-equilibrium wall-model based on unsteady 3D Reynolds-averaged Navier-Stokes (RANS) equations has been implemented in an unstructured mesh environment. The method is similar to that of the wall-model for structured mesh described by Wang and Moin [Phys. Fluids 14, 2043-2051 (2002)], but is supplemented by a new dynamic eddy viscosity/conductivity model that corrects the effect of the resolved Reynolds stress (resolved turbulent heat flux) on the skin friction (wall heat flux). This correction is crucial in predicting the correct level of the skin friction. Unlike earlier models, this eddy viscosity/conductivity model does not have a stress-matching procedure or a tunable free parameter, and it shows consistent performance over a wide range of Reynolds numbers. The wall-model is validated against canonical (attached) transitional and fully turbulent flows at moderate to very high Reynolds numbers: a turbulent channel flow at Reτ = 2000, an H-type transitional boundary layer up to Reθ = 3300, and a high Reynolds number boundary layer at Reθ = 31 000. Application to a separated flow over a NACA4412 airfoil operating close to maximum lift is also considered to test the performance of the wall-model in complex non-equilibrium flows.
Novel non-equilibrium modelling of a DC electric arc in argon
NASA Astrophysics Data System (ADS)
Baeva, M.; Benilov, M. S.; Almeida, N. A.; Uhrlandt, D.
2016-06-01
A novel non-equilibrium model has been developed to describe the interplay of heat and mass transfer and electric and magnetic fields in a DC electric arc. A complete diffusion treatment of particle fluxes, a generalized form of Ohm’s law, and numerical matching of the arc plasma with the space-charge sheaths adjacent to the electrodes are applied to analyze in detail the plasma parameters and the phenomena occurring in the plasma column and the near-electrode regions of a DC arc generated in atmospheric pressure argon for current levels from 20 A up to 200 A. Results comprising electric field and potential, current density, heating of the electrodes, and effects of thermal and chemical non-equilibrium are presented and discussed. The current-voltage characteristic obtained is in fair agreement with known experimental data. It indicates a minimum for arc current of about 80 A. For all current levels, a field reversal in front of the anode accompanied by a voltage drop of (0.7-2.6) V is observed. Another field reversal is observed near the cathode for arc currents below 80 A.
NASA Astrophysics Data System (ADS)
English, Niall J.; Clarke, Elaine T.
2013-09-01
Equilibrium and non-equilibrium molecular dynamics (MD) simulations have been performed to investigate thermal-driven break-up of planar CO2 hydrate interfaces in liquid water at 300-320 K. Different guest compositions, at 85%, 95%, and 100% of maximum theoretical occupation, led to statistically-significant differences in the observed initial dissociation rates. The melting temperatures of each interface were estimated, and dissociation rates were observed to be strongly dependent on temperature, with higher dissociation rates at larger over-temperatures vis-à-vis melting. A simple coupled mass and heat transfer model developed previously was applied to fit the observed dissociation profiles, and this helps to identify clearly two distinct régimes of break-up; a second well-defined region is essentially independent of composition and temperature, in which the remaining nanoscale, de facto two-dimensional system's lattice framework is intrinsically unstable. From equilibrium MD of the two-phase systems at their melting point, the relaxation times of the auto-correlation functions of fluctuations in number of enclathrated guest molecules were used as a basis for comparison of the variation in the underlying, non-equilibrium, thermal-driven dissociation rates via Onsager's hypothesis, and statistically significant differences were found, confirming the value of a fluctuation-dissipation approach in this case.
NASA Astrophysics Data System (ADS)
Mozetic, Miran
2011-05-01
A promising method for the synthesis of metal oxide nanowires is based on the application of the extremely non-equilibrium gaseous environment found in oxygen plasma created by some types of discharges. The kinetic temperature of neutral gas is kept close to the room temperature, the electron temperature is a few eV, the ionization fraction below 10-6 and the dissociation fraction close to 100%. Plasma with such characteristics is obtained using electrodeless high frequency discharges driven by radiofrequency or microwave generators. Plasma parameters such as the electron density and energy distribution function, the Debye length, the dissociation and ionization fractions, the density of negatively charged molecules, the ratio between the positively charged molecules and atoms and the distribution of atoms and molecules over excited states depend on discharge parameters. The most important discharge parameters are the generator power, frequency and coupling, the purity and pressure of working gas and the gas flow, the dimensions of the discharge chamber, the materials facing plasma, the residual atmosphere, and, usually very importantly though often neglected, the properties of the samples mounted into a discharge chamber. Proper construction of the experimental system for the synthesis of metal oxide nanowires allows for almost 100% dissociation fraction and thus extremely rapid growing of nanowires. The particularities of oxygen plasma as well as real-time monitoring of the dissociation fraction are elaborated in this contribution. The lack of reliable experimental results on characterization of extremely non-equilibrium oxygen plasma is stressed.
New directions in fluid dynamics: non-equilibrium aerodynamic and microsystem flows.
Reese, Jason M; Gallis, Michael A; Lockerby, Duncan A
2003-12-15
Fluid flows that do not have local equilibrium are characteristic of some of the new frontiers in engineering and technology, for example, high-speed high-altitude aerodynamics and the development of micrometre-sized fluid pumps, turbines and other devices. However, this area of fluid dynamics is poorly understood from both the experimental and simulation perspectives, which hampers the progress of these technologies. This paper reviews some of the recent developments in experimental techniques and modelling methods for non-equilibrium gas flows, examining their advantages and drawbacks. We also present new results from our computational investigations into both hypersonic and microsystem flows using two distinct numerical methodologies: the direct simulation Monte Carlo method and extended hydrodynamics. While the direct simulation approach produces excellent results and is used widely, extended hydrodynamics is not as well developed but is a promising candidate for future more complex simulations. Finally, we discuss some of the other situations where these simulation methods could be usefully applied, and look to the future of numerical tools for non-equilibrium flows.
Non-equilibrium disordered Bose gases: condensation, superfluidity and dynamical Bose glass
NASA Astrophysics Data System (ADS)
Chen, Lei; Liang, Zhaoxin; Hu, Ying; Zhang, Zhidong
2016-01-01
In an equilibrium three-dimensional (3D) disordered condensate, it is well established that disorder can generate an amount of normal fluid ρ n equaling to 4/3 of ρ ex , where ρ ex is a sum of interaction-induced quantum depletion and disorder-induced condensate deformation. The concept that the superfluid is more volatile to the existence of disorder than the condensate is crucial to the understanding of the Bose glass phase. In this work, we show that, by bringing a weakly disordered 3D condensate to non-equilibrium regime via a quantum quench in the interaction, disorder can destroy superfluid significantly more, leading to a steady state of Hamiltonian H f in which the ρ n far exceeds 4/3 of the ρ ex . This suggests the possibility of engineering Bose glass in the dynamic regime. Here, we refer to the dynamical Bose glass as the case where in the steady state of quenched condensate, the superfluid density goes to zero while the condensate density remains finite. As both the ρ n and ρ ex are measurable quantities, our results allow an experimental demonstration of the dramatized interplay between the disorder and interaction in the non-equilibrium scenario.
Path-space variational inference for non-equilibrium coarse-grained systems
NASA Astrophysics Data System (ADS)
Harmandaris, Vagelis; Kalligiannaki, Evangelia; Katsoulakis, Markos; Plecháč, Petr
2016-06-01
In this paper we discuss information-theoretic tools for obtaining optimized coarse-grained molecular models for both equilibrium and non-equilibrium molecular simulations. The latter are ubiquitous in physicochemical and biological applications, where they are typically associated with coupling mechanisms, multi-physics and/or boundary conditions. In general the non-equilibrium steady states are not known explicitly as they do not necessarily have a Gibbs structure. The presented approach can compare microscopic behavior of molecular systems to parametric and non-parametric coarse-grained models using the relative entropy between distributions on the path space and setting up a corresponding path-space variational inference problem. The methods can become entirely data-driven when the microscopic dynamics are replaced with corresponding correlated data in the form of time series. Furthermore, we present connections and generalizations of force matching methods in coarse-graining with path-space information methods. We demonstrate the enhanced transferability of information-based parameterizations to different observables, at a specific thermodynamic point, due to information inequalities. We discuss methodological connections between information-based coarse-graining of molecular systems and variational inference methods primarily developed in the machine learning community. However, we note that the work presented here addresses variational inference for correlated time series due to the focus on dynamics. The applicability of the proposed methods is demonstrated on high-dimensional stochastic processes given by overdamped and driven Langevin dynamics of interacting particles.
Single-molecule measurement of the effective temperature in non-equilibrium steady states
NASA Astrophysics Data System (ADS)
Dieterich, E.; Camunas-Soler, J.; Ribezzi-Crivellari, M.; Seifert, U.; Ritort, F.
2015-11-01
Temperature is a well-defined quantity for systems in equilibrium. For glassy systems, it has been extended to the non-equilibrium regime, showing up as an effective quantity in a modified version of the fluctuation-dissipation theorem. However, experimental evidence supporting this definition remains scarce. Here, we present the first direct experimental demonstration of the effective temperature by measuring correlations and responses in single molecules in non-equilibrium steady states generated under external random forces. We combine experiment, analytical theory and simulations for systems with different levels of complexity, ranging from a single bead in an optical trap to two-state and multiple-state DNA hairpins. From these data, we extract a unifying picture for the existence of an effective temperature based on the relative order of various timescales characterizing intrinsic relaxation and external driving. Our study thus introduces driven small systems as a fertile ground to address fundamental concepts in statistical physics, condensed-matter physics and biophysics.
Graphical representation for isothermal kinetics of non-equilibrium grain-boundary segregation
Wang Kai; Xu Tingdong; Song Shenhua; Shao Chong
2011-06-15
A model of non-equilibrium grain-boundary segregation of solute is expressed with graphs for the isothermal aging at various temperatures after quenching from a solution temperature. It is found from the graphical representations that when the samples are aged for a certain time at various temperatures there is a maximum value in the segregation concentration at a certain temperature. The aging time is equal or close to the critical time of non-equilibrium segregation corresponding to this temperature. This finding is experimentally confirmed with sulfur in an Ni-base superalloy with the aid of Auger electron spectroscopy. As an application of the new finding, a mechanism for intermediate temperature embrittlement of alloys is suggested and identified experimentally with tension tests of the superalloy. - Research Highlights: {yields} A peak of solute segregation emerges at a temperature when aging for a certain time at various temperatures after quenching. {yields} The aging time is equal or close to the critical time of segregation at this temperature. {yields} This finding is experimentally confirmed in an Ni-Cr-Fe superalloy. {yields} A mechanism for intermediate temperature embrittlement of alloys is proposed.
A non-equilibrium state diagram for liquid/fluid/particle mixtures.
Velankar, Sachin S
2015-11-21
The equilibrium structures of ternary oil/water/surfactant systems are often represented within a triangular composition diagram with various regions of the triangle corresponding to different equilibrium states. We transplant this idea to ternary liquid/fluid/particle systems that are far from equilibrium. Liquid/liquid/particle mixtures or liquid/gas/particle mixtures yield a wide diversity of morphologies including Pickering emulsions, bijels, pendular aggregates, spherical agglomerates, capillary suspensions, liquid marbles, powdered liquids, and particle-stabilized foams. This paper argues that such ternary liquid/fluid/particle mixtures can be unified into a non-equilibrium state diagram. What is common among all these systems is that the morphology results from an interplay between the preferential wettability of the particles, capillarity, and viscous forces encountered during mixing. Therefore all such systems share certain universal features, regardless of the details of the particles or fluids used. These features guide the construction of a non-equilibrium state diagram which takes the form of a triangular prism, where each triangular cross-section of the prism corresponds to a different relative affinity of the particles towards the two fluids. We classify the prism into regions in which the various morphologies appear and also emphasize the major difference between systems in which the particles are fully-wetted by one of the fluids vs. partially-wetted by both fluids. We also discuss how the state diagram may change with mixing intensity or with interparticle attractions.
Non-equilibrium dynamics and floral trait interactions shape extant angiosperm diversity.
O'Meara, Brian C; Smith, Stacey D; Armbruster, W Scott; Harder, Lawrence D; Hardy, Christopher R; Hileman, Lena C; Hufford, Larry; Litt, Amy; Magallón, Susana; Smith, Stephen A; Stevens, Peter F; Fenster, Charles B; Diggle, Pamela K
2016-05-11
Why are some traits and trait combinations exceptionally common across the tree of life, whereas others are vanishingly rare? The distribution of trait diversity across a clade at any time depends on the ancestral state of the clade, the rate at which new phenotypes evolve, the differences in speciation and extinction rates across lineages, and whether an equilibrium has been reached. Here we examine the role of transition rates, differential diversification (speciation minus extinction) and non-equilibrium dynamics on the evolutionary history of angiosperms, a clade well known for the abundance of some trait combinations and the rarity of others. Our analysis reveals that three character states (corolla present, bilateral symmetry, reduced stamen number) act synergistically as a key innovation, doubling diversification rates for lineages in which this combination occurs. However, this combination is currently less common than predicted at equilibrium because the individual characters evolve infrequently. Simulations suggest that angiosperms will remain far from the equilibrium frequencies of character states well into the future. Such non-equilibrium dynamics may be common when major innovations evolve rarely, allowing lineages with ancestral forms to persist, and even outnumber those with diversification-enhancing states, for tens of millions of years. PMID:27147092
Non-Equilibrium Dynamics of C-QED Arrays in Strong Correlation Regime
NASA Astrophysics Data System (ADS)
Zhang, Xin-Ding; Li, Zhi-Hang; Zhang, Xiao-Ming
2016-07-01
Recently increasing interests are attracted in the physics of controlled arrays of nonlinear cavity resonators because of the rapid experimental progress achieved in cavity and circuit quantum electrodynamics (QED). For a driven-dissipative two-dimentional planar C-QED array, standard Markov master equation is generally used to study the dynamics of this system. However, when in the case that the on-site photon-photon interaction enters strong correlation regime, standard Markov master equation may lead to incorrect results. In this paper we study the non-equilibrium dynamics of a two-dimentional C-QED array, which is homogeneously pumped by an external pulse, at the same time dissipation exits. We study the evolution of the average photon number of a single cavity by deriving a modified master equation to. In comparison with the standard master equation, the numerical result obtained by our newly derived master equation shows significant difference for the non-equilibrium dynamics of the system.
Fiber Bragg grating dynamic demodulation based on non-equilibrium interferometry
NASA Astrophysics Data System (ADS)
Yu, Qi; Jing, Zhenguo; Peng, Wei; Zhang, Xinpu; Liu, Yun; Xing, Chuanqi; Li, Hong; Yao, Wenjuan
2011-12-01
Non-equilibrium interferometric Fiber Bragg Grating (FBG) sensor is suitable for the accurate measurements of high-frequency dynamic stress, vibration, etc because of its high sensitivity and high frequency response compared to other types of FBG sensors. In this paper, a Phase Generation Carrier (PGC) demodulation technique of non-equilibrium interferometric FBG sensor that based on ARCTAN algorithm by using an arctangent algorithm with a simple method, has been investigated ,which can avoid the high-frequency noise increases, the error accumulation, the integrator signal jump of the integrator and other inherent weaknesses in the system. ARCTAN has a better response characteristic of the mutant signals, especially for low-frequency large-signal that can be demodulated with a greater range. The experimental result demonstrate that implementing measured resolution can up to 10nɛ/√Hz@500Hz in vibration strain, a signal sampling rate to 100 KHz and a frequency response range up to 1 KHz. This method can improve the performance of the system greatly which has potential significance for practical sensor application.
Cooling and Non-equilibrium Motion of an Ultracold Atomic Gas using Synthetic Thermal Bodies
NASA Astrophysics Data System (ADS)
Price, Craig; Liu, Qi; Zhao, Jianshi; Gemelke, Nathan
2016-05-01
We describe the non-equilibrium behavior of atomic gases immersed in synthetic thermal environments created by engineered statistical reservoirs of spatio-temporally disordered light. By dynamically modulating the modal distribution of an optical fiber carrying far off-resonant light, optical dipole potentials are created for 87 Rb atoms with specified spatial and temporal spectra. Additional coupling to thermal reserviors defined by time-dependent radio-frequency-induced hyperfine spin-couplings offers a wide range of control over thermal excitations. By controlling the statistical properties of the baths, diffusive motion can be tailored in real-time, and transport can be controlled even at ultra-cold temperatures below the photon recoil. The use of an effectively statistical classical body opens new avenues for quantum simulation, and offers opportunities for study of systems governed by effective hamiltonians which are themselves poised near critical points, and the simulation of effectively many-body systems through the non-equilibrium motion of single atoms.
Croccolo, Fabrizio; Bataller, Henri; Scheffold, Frank
2014-11-01
In a binary fluid mixture subject to gravity and a stabilizing concentration gradient, concentration non-equilibrium fluctuations are long-ranged. While the gradient leads to an enhancement of the respective equilibrium fluctuations, the effect of gravity is a damping of fluctuations larger than a "characteristic" size. This damping is visible both in the fluctuation power spectrum probed by static and the temporal correlation function probed by dynamic light scattering. One aspect of the "characteristic" size can be appreciated by the dynamic analysis; in fact at the corresponding "characteristic" wave vector q* one can observe a maximum of the fluctuation time constant indicating the more persistent fluctuation of the system. Also in the static analysis a "characteristic" size can be extracted from the crossover wave vector. According to common theoretical concepts, the result should be the same in both cases. In the present work we provide evidence for a systematic difference in the experimentally observed "characteristic" size as obtained by static and dynamic measurements. Our observation thus points out the need for a more refined theory of non-equilibrium concentration fluctuations.
Time-dependent non-equilibrium dielectric response in QM/continuum approaches.
Ding, Feizhi; Lingerfelt, David B; Mennucci, Benedetta; Li, Xiaosong
2015-01-21
The Polarizable Continuum Models (PCMs) are some of the most inexpensive yet successful methods for including the effects of solvation in quantum-mechanical calculations of molecular systems. However, when applied to the electronic excitation process, these methods are restricted to dichotomously assuming either that the solvent has completely equilibrated with the excited solute charge density (infinite-time limit), or that it retains the configuration that was in equilibrium with the solute prior to excitation (zero-time limit). This renders the traditional PCMs inappropriate for resolving time-dependent solvent effects on non-equilibrium solute electron dynamics like those implicated in the instants following photoexcitation of a solvated molecular species. To extend the existing methods to this non-equilibrium regime, we herein derive and apply a new formalism for a general time-dependent continuum embedding method designed to be propagated alongside the solute's electronic degrees of freedom in the time domain. Given the frequency-dependent dielectric constant of the solvent, an equation of motion for the dielectric polarization is derived within the PCM framework and numerically integrated simultaneously with the time-dependent Hartree fock/density functional theory equations. Results for small molecular systems show the anticipated dipole quenching and electronic state dephasing/relaxation resulting from out-of-phase charge fluctuations in the dielectric and embedded quantum system.
Time-dependent non-equilibrium dielectric response in QM/continuum approaches
Ding, Feizhi; Lingerfelt, David B.; Li, Xiaosong E-mail: li@chem.washington.edu; Mennucci, Benedetta E-mail: li@chem.washington.edu
2015-01-21
The Polarizable Continuum Models (PCMs) are some of the most inexpensive yet successful methods for including the effects of solvation in quantum-mechanical calculations of molecular systems. However, when applied to the electronic excitation process, these methods are restricted to dichotomously assuming either that the solvent has completely equilibrated with the excited solute charge density (infinite-time limit), or that it retains the configuration that was in equilibrium with the solute prior to excitation (zero-time limit). This renders the traditional PCMs inappropriate for resolving time-dependent solvent effects on non-equilibrium solute electron dynamics like those implicated in the instants following photoexcitation of a solvated molecular species. To extend the existing methods to this non-equilibrium regime, we herein derive and apply a new formalism for a general time-dependent continuum embedding method designed to be propagated alongside the solute’s electronic degrees of freedom in the time domain. Given the frequency-dependent dielectric constant of the solvent, an equation of motion for the dielectric polarization is derived within the PCM framework and numerically integrated simultaneously with the time-dependent Hartree fock/density functional theory equations. Results for small molecular systems show the anticipated dipole quenching and electronic state dephasing/relaxation resulting from out-of-phase charge fluctuations in the dielectric and embedded quantum system.
Non-equilibrium oxidation states of zirconium during early stages of metal oxidation
Ma, Wen; Senanayake, Sanjaya D.; Herbert, F. William; Yildiz, Bilge
2015-03-11
The chemical state of Zr during the initial, self-limiting stage of oxidation on single crystal zirconium (0001), with oxide thickness on the order of 1 nm, was probed by synchrotron x-ray photoelectron spectroscopy. Quantitative analysis of the Zr 3d spectrum by the spectrum reconstruction method demonstrated the formation of Zr^{1+}, Zr^{2+}, and Zr^{3+} as non-equilibrium oxidation states, in addition to Zr^{4+} in the stoichiometric ZrO_{2}. This finding resolves the long-debated question of whether it is possible to form any valence states between Zr^{0} and Zr^{4+} at the metal-oxide interface. As a result, the presence of local strong electric fields and the minimization of interfacial energy are assessed and demonstrated as mechanisms that can drive the formation of these non-equilibrium valence states of Zr.
Equilibrium and non-equilibrium cluster phases in colloids with competing interactions.
Mani, Ethayaraja; Lechner, Wolfgang; Kegel, Willem K; Bolhuis, Peter G
2014-07-01
The phase behavior of colloids that interact via competing interactions - short-range attraction and long-range repulsion - is studied by computer simulation. In particular, for a fixed strength and range of repulsion, the effect of the strength of an attractive interaction (ε) on the phase behavior is investigated at various colloid densities (ρ). A thermodynamically stable equilibrium colloidal cluster phase, consisting of compact crystalline clusters, is found below the fluid-solid coexistence line in the ε-ρ parameter space. The mean cluster size is found to linearly increase with the colloid density. At large ε and low densities, and at small ε and high densities, a non-equilibrium cluster phase, consisting of elongated Bernal spiral-like clusters, is observed. Although gelation can be induced either by increasing ε at constant density or vice versa, the gelation mechanism is different in either route. While in the ρ route gelation occurs via a glass transition of compact clusters, gelation in the ε route is characterized by percolation of elongated clusters. This study both provides the location of equilibrium and non-equilibrium cluster phases with respect to the fluid-solid coexistence, and reveals the dependencies of the gelation mechanism on the preparation route.
Hsp70 chaperones are non-equilibrium machines that achieve ultra-affinity by energy consumption.
De Los Rios, Paolo; Barducci, Alessandro
2014-05-27
70-kDa Heat shock proteins are ATP-driven molecular chaperones that perform a myriad of essential cellular tasks. Although structural and biochemical studies have shed some light on their functional mechanism, the fundamental issue of the role of energy consumption, due to ATP-hydrolysis, has remained unaddressed. Here we establish a clear connection between the non-equilibrium nature of Hsp70, due to ATP hydrolysis, and the determining feature of its function, namely its high affinity for its substrates. Energy consumption can indeed decrease the dissociation constant of the chaperone-substrate complex by several orders of magnitude with respect to an equilibrium scenario. We find that the biochemical requirements for observing such ultra-affinity coincide with the physiological conditions in the cell. Our results rationalize several experimental observations and pave the way for further analysis of non-equilibrium effects underlying chaperone functions.DOI: http://dx.doi.org/10.7554/eLife.02218.001.
Wu, Wei; Wang, Jin
2014-09-14
We have established a general non-equilibrium thermodynamic formalism consistently applicable to both spatially homogeneous and, more importantly, spatially inhomogeneous systems, governed by the Langevin and Fokker-Planck stochastic dynamics with multiple state transition mechanisms, using the potential-flux landscape framework as a bridge connecting stochastic dynamics with non-equilibrium thermodynamics. A set of non-equilibrium thermodynamic equations, quantifying the relations of the non-equilibrium entropy, entropy flow, entropy production, and other thermodynamic quantities, together with their specific expressions, is constructed from a set of dynamical decomposition equations associated with the potential-flux landscape framework. The flux velocity plays a pivotal role on both the dynamic and thermodynamic levels. On the dynamic level, it represents a dynamic force breaking detailed balance, entailing the dynamical decomposition equations. On the thermodynamic level, it represents a thermodynamic force generating entropy production, manifested in the non-equilibrium thermodynamic equations. The Ornstein-Uhlenbeck process and more specific examples, the spatial stochastic neuronal model, in particular, are studied to test and illustrate the general theory. This theoretical framework is particularly suitable to study the non-equilibrium (thermo)dynamics of spatially inhomogeneous systems abundant in nature. This paper is the second of a series.
NASA Astrophysics Data System (ADS)
Wu, Wei; Wang, Jin
2014-09-01
We have established a general non-equilibrium thermodynamic formalism consistently applicable to both spatially homogeneous and, more importantly, spatially inhomogeneous systems, governed by the Langevin and Fokker-Planck stochastic dynamics with multiple state transition mechanisms, using the potential-flux landscape framework as a bridge connecting stochastic dynamics with non-equilibrium thermodynamics. A set of non-equilibrium thermodynamic equations, quantifying the relations of the non-equilibrium entropy, entropy flow, entropy production, and other thermodynamic quantities, together with their specific expressions, is constructed from a set of dynamical decomposition equations associated with the potential-flux landscape framework. The flux velocity plays a pivotal role on both the dynamic and thermodynamic levels. On the dynamic level, it represents a dynamic force breaking detailed balance, entailing the dynamical decomposition equations. On the thermodynamic level, it represents a thermodynamic force generating entropy production, manifested in the non-equilibrium thermodynamic equations. The Ornstein-Uhlenbeck process and more specific examples, the spatial stochastic neuronal model, in particular, are studied to test and illustrate the general theory. This theoretical framework is particularly suitable to study the non-equilibrium (thermo)dynamics of spatially inhomogeneous systems abundant in nature. This paper is the second of a series.
The development of a non-equilibrium dispersed flow film boiling heat transfer modeling package
NASA Astrophysics Data System (ADS)
Meholic, Michael J.
The dispersed flow film boiling (DFFB) heat transfer regime is important to several applications including cryogenics, rocket engines, steam generators, and in the safety analysis of nuclear reactors. Most notably, DFFB is responsible for the heat transfer during the blowdown and reflood portions of the postulated loss-of-coolant-accident (LOCA). Such analyses require the accurate predictions of the heat transfer resulting from the non-equilibrium conditions present in DFFB. A total of six, interrelated heat transfer paths need to be modeled accurately in order to quantify DFFB heat transfer. Within the nuclear industry, transient safety analysis codes, such as COBRA-TF, are used to ensure the safety of the reactor under various transient and accident scenarios. An extensive literature review of DFFB heat transfer highlighted a number of correlative, phenomenological, and mechanistic models. The Forslund-Rohsenow model is most commonly implemented throughout the nuclear industry. However, several of the models suggested by Forslund and Rohsenow to model DFFB phenomena are either inapplicable for nuclear reactors or do not provide an accurate physical representation of the true situation. Deficiencies among other DFFB heat transfer models in their applicability to nuclear reactors or in their computational expenses motivated the development of a mechanistically based DFFB model which accounted for each heat transfer mechanism explicitly. The heat transfer resulting from dispersed droplets contacting the heated wall in DFFB was often neglected in previous models. In this work, a first-principles approach was implemented to quantify the heat transfer attributed to direct contact. Lagrangian droplet trajectory calculations incorporating realistic radial vapor velocity and temperature profiles were performed to determine if droplets could contact the heated wall based upon the local conditions. These calculations were performed over a droplet size spectrum accounting
EVALUATION OF SIGNIFICANT ANTHROPOGENIC SOURCES OF RADIATIVELY IMPORTANT TRACE GASES
The report is an initial evaluation of significant anthropogenic sources of radiatively important trace gases. missions of greenhouse gases from human activities--including fossil fuel combustion, industrial/agricultural activities, and transportation--contribute to the increasin...
Stability of high-brilliance synchrotron radiation sources
Chattopadhyay, S.
1989-12-01
This paper discusses the following topics: characteristics of synchrotron radiation sources; stability of the orbits; orbit control; nonlinear dynamic stability; and coherent stability and control. 1 ref., 5 figs., 1 tab. (LSP)
NASA Astrophysics Data System (ADS)
Liu, Cheng-Wei
Phase transitions and their associated critical phenomena are of fundamental importance and play a crucial role in the development of statistical physics for both classical and quantum systems. Phase transitions embody diverse aspects of physics and also have numerous applications outside physics, e.g., in chemistry, biology, and combinatorial optimization problems in computer science. Many problems can be reduced to a system consisting of a large number of interacting agents, which under some circumstances (e.g., changes of external parameters) exhibit collective behavior; this type of scenario also underlies phase transitions. The theoretical understanding of equilibrium phase transitions was put on a solid footing with the establishment of the renormalization group. In contrast, non-equilibrium phase transition are relatively less understood and currently a very active research topic. One important milestone here is the Kibble-Zurek (KZ) mechanism, which provides a useful framework for describing a system with a transition point approached through a non-equilibrium quench process. I developed two efficient Monte Carlo techniques for studying phase transitions, one is for classical phase transition and the other is for quantum phase transitions, both are under the framework of KZ scaling. For classical phase transition, I develop a non-equilibrium quench (NEQ) simulation that can completely avoid the critical slowing down problem. For quantum phase transitions, I develop a new algorithm, named quasi-adiabatic quantum Monte Carlo (QAQMC) algorithm for studying quantum quenches. I demonstrate the utility of QAQMC quantum Ising model and obtain high-precision results at the transition point, in particular showing generalized dynamic scaling in the quantum system. To further extend the methods, I study more complex systems such as spin-glasses and random graphs. The techniques allow us to investigate the problems efficiently. From the classical perspective, using the
Elastic Wave Radiation from a Line Source of Finite Length
Aldridge, D.F.
1998-11-04
Straightforward algebraic expressions describing the elastic wavefield produced by a line source of finite length are derived in circular cylindrical coordinates. The surrounding elastic medium is assumed to be both homogeneous and isotropic, anc[ the source stress distribution is considered axisymmetic. The time- and space-domain formulae are accurate at all distances and directions from the source; no fa-field or long-wavelength assumptions are adopted for the derivation. The mathematics yield a unified treatment of three different types of sources: an axial torque, an axial force, and a radial pressure. The torque source radiates only azirnuthally polarized shear waves, whereas force and pressure sources generate simultaneous compressional and shear radiation polarized in planes containing the line source. The formulae reduce to more familiar expressions in the two limiting cases where the length of the line source approaches zero and infinity. Far-field approximations to the exact equations indicate that waves radiated parallel to the line source axI.s are attenuated relative to those radiated normal to the axis. The attenuation is more severe for higher I?equencies and for lower wavespeeds. Hence, shear waves are affected more than compressional waves. This fi-equency- and directiondependent attenuation is characterized by an extremely simple mathematical formula, and is readily apparent in example synthetic seismograms.
The Advanced Light Source (ALS) Radiation Safety System. Revised
Ritchie, A.L.; Oldfather, D.E.; Lindner, A.F.
1993-08-01
The Advanced Light Source (ALS) at the Lawrence Berkeley Laboratory (LBL) is a 1.5 Gev synchrotron light source facility consisting of a 120 kev electron gun, 50 Mev linear accelerator, 1.5 Gev booster synchrotron, 200 meter circumference electron storage ring, and many photon beamline transport systems for research. Figure 1. ALS floor plan. Pairs of neutron and gamma radiation monitors are shown as dots numbered from 1 to 12. The Radiation Safety System for the ALS has been designed and built with a primary goal of providing protection against inadvertent personnel exposure to gamma and neutron radiation and, secondarily, to enhance the electrical safety of select magnet power supplies.
Contact resistances in trigate and FinFET devices in a non-equilibrium Green's functions approach
NASA Astrophysics Data System (ADS)
Bourdet, Léo; Li, Jing; Pelloux-Prayer, Johan; Triozon, François; Cassé, Mikaël; Barraud, Sylvain; Martinie, Sébastien; Rideau, Denis; Niquet, Yann-Michel
2016-02-01
We compute the contact resistances Rc in trigate and FinFET devices with widths and heights in the 4-24 nm range using a Non-Equilibrium Green's Functions approach. Electron-phonon, surface roughness, and Coulomb scattering are taken into account. We show that Rc represents a significant part of the total resistance of devices with sub-30 nm gate lengths. The analysis of the quasi-Fermi level profile reveals that the spacers between the heavily doped source/drain and the gate are major contributors to the contact resistance. The conductance is indeed limited by the poor electrostatic control over the carrier density under the spacers. We then disentangle the ballistic and diffusive components of Rc and analyze the impact of different design parameters (cross section and doping profile in the contacts) on the electrical performances of the devices. The contact resistance and variability rapidly increase when the cross sectional area of the channel goes below ≃50 nm2. We also highlight the role of the charges trapped at the interface between silicon and the spacer material.
A millimeter wavelength radiation source using a dual grating resonator
Killoran, J.H.; Hacker, F.L.; Walsh, J.E. . Dept. of Physics)
1994-10-01
A novel means of producing coherent radiation by passing an electron through a dual-grating resonator is presented. The observed radiation is in accordance with the Smith-Purcell dispersion relation for a single grating. Feedback is provided by a second grating. Experiments carried out at beam energies from 30--55 KeV produced radiation at wavelengths from 6 to 0.75 mm. Power measurements were used to clarify the grating-beam interaction. Indications are that operation could be easily extended to shorter wavelengths to provide an inexpensive and compact radiation source in the far-infrared.
The Radiation, Interplanetary Shocks, and Coronal Sources (RISCS) Toolset
NASA Technical Reports Server (NTRS)
Zank, G. P.; Spann, James F.
2014-01-01
The goal of this project is to serve the needs of space system designers and operators by developing an interplanetary radiation environment model within 10 AU:Radiation, Interplanetary Shocks, and Coronal Sources (RISCS) toolset: (1) The RISCS toolset will provide specific reference environments for space system designers and nowcasting and forecasting capabilities for space system operators; (2) We envision the RISCS toolset providing the spatial and temporal radiation environment external to the Earth's (and other planets') magnetosphere, as well as possessing the modularity to integrate separate applications (apps) that can map to specific magnetosphere locations and/or perform the subsequent radiation transport and dosimetry for a specific target.
Low dissipation in non-equilibrium control: sampling the ensemble of efficient protocols
NASA Astrophysics Data System (ADS)
Rotskoff, Grant; Gingrich, Todd; Crooks, Gavin; Geissler, Phillip
Designing schemes to efficiently control fluctuating, non-equilibrium systems is problem of fundamental importance and tremendous practical interest. A number of optimization techniques have proven fruitful in the pursuit of optimal control, but these approaches focus on the singular goal of finding the exact, optimal protocol. Here, we investigate the diversity of protocols that achieve low dissipation with a Monte Carlo path sampling algorithm. Akin to Boltzmann weighting configurations in Metropolis Monte Carlo, each protocol is exponentially biased by its mean dissipation. We show that the ensemble of low dissipation protocols can be sampled exactly in the Gaussian limit and that the method continues to robustly generate low dissipation protocols, even as the external control drives the system far from equilibrium.
An alternative order-parameter for non-equilibrium generalized spin models on honeycomb lattices
NASA Astrophysics Data System (ADS)
Sastre, Francisco; Henkel, Malte
2016-04-01
An alternative definition for the order-parameter is proposed, for a family of non-equilibrium spin models with up-down symmetry on honeycomb lattices, and which depends on two parameters. In contrast to the usual definition, our proposal takes into account that each site of the lattice can be associated with a local temperature which depends on the local environment of each site. Using the generalised voter motel as a test case, we analyse the phase diagram and the critical exponents in the stationary state and compare the results of the standard order-parameter with the ones following from our new proposal, on the honeycomb lattice. The stationary phase transition is in the Ising universality class. Finite-size corrections are also studied and the Wegner exponent is estimated as ω =1.06(9).
Effects of non-equilibrium particle distributions in deuterium-tritium burning
Michta, D; Graziani, F; Pruet, J; Luu, T
2009-08-18
We investigate the effects of non-equilibrium particle distributions resulting from rapid deuterium-tritium burning in plasmas using a Fokker-Planck code that incorporates small-angle Coulomb scattering, Brehmsstrahlung, Compton scattering, and thermal-nuclear burning. We find that in inertial confinement fusion environments, deviations away from Maxwellian distributions for either deuterium or tritium ions are small and result in 1% changes in the energy production rates. The deuterium and tritium effective temperatures are not equal, but differ by only about 2.5% near the time of peak burn rate. Simulations with high Z (Xe) dopants show that the dopant temperature closely tracks that of the fuel. On the other hand, fusion product ion distributions are highly non-Maxwellian, and careful treatments of energy-exchange between these ions and other particles is important for determining burn rates.
Collective Flocking Dynamics: Long Rang Order in a Non-Equilibrium 2D XY Model
NASA Astrophysics Data System (ADS)
Tu, Yuhai
1996-03-01
We propose and study a non-equilibrium continuum dynamical model for the collective motion of large groups of biological organisms (e.g., flocks of birds, slime molds, schools of fishs, etc.) (J. Toner and Y. Tu, Phys. Rev. Lett.), 75(23), 4326(1995) Our model becomes highly non-trivial, and different from the equilibrium model, for d
Processing and crystallographic structure of non-equilibrium Si-doped HfO{sub 2}
Hou, Dong; Fancher, Chris M.; Esteves, Giovanni; Jones, Jacob L.; Zhao, Lili
2015-06-28
Si-doped HfO{sub 2} was confirmed to exist as a non-equilibrium state. The crystallographic structures of Si-doped HfO{sub 2} were studied using high-resolution synchrotron X-ray diffraction and the Rietveld refinement method. Incorporation of Si into HfO{sub 2} and diffusion of Si out of (Hf,Si)O{sub 2} were determined as a function of calcination temperature. Higher thermal energy input at elevated calcination temperatures resulted in the formation of HfSiO{sub 4}, which is the expected major secondary phase in Si-doped HfO{sub 2}. The effect of SiO{sub 2} particle size (nano- and micron-sized) on the formation of Si-doped HfO{sub 2} was also determined. Nano-crystalline SiO{sub 2} was found to incorporate into HfO{sub 2} more readily.
NASA Astrophysics Data System (ADS)
Mo, M. Y.; Kantorovich, L.
2001-02-01
We apply the non-equilibrium statistical operator method to non-contact atomic force microscopy, considering explicitly the statistical effects of (classical) vibrations of surface atoms and associated energy transfer from the tip to the surface. We derive several, physically and mathematically equivalent, forms of the equation of motion for the tip, each containing a friction term due to the so-called intrinsic mechanism of energy dissipation first suggested by Gauthier and Tsukada. Our exact treatment supports the results of some earlier work which were all approximate. We also demonstrate, using the same theory, that the distribution function of the tip in the coordinate-momentum phase subspace is governed by the Fokker-Planck equation and should be considered as strongly peaked around the exact values t and t of the momentum and the position of the tip, respectively.
Charge states of energetic tellurium ions: Equilibrium and non-equilibrium calculations
NASA Astrophysics Data System (ADS)
Kartavykh, Y.; Droege, W.; Klecker, B.; Kocharov, L.; Moebius, E.
2007-12-01
Recently, very high abundances of ultraheavy ions were observed in impulsive SEP events, compared to coronal abundances with enrichment factors of >100 for atomic mass > 100 amu. Because wave/particle interaction processes, as discussed for heavy ion enrichment and acceleration, depend critically on the mass per charge (M/Q) of the ions, an estimate of the ionic charge is very important for model calculations. In any realistic acceleration model one would have to use the ionization and recombination rates of these ions as a function of energy, because charge changing processes in the solar corona are inevitable and energy dependent. As an example of high mass ions, we calculate the equilibrium and non-equilibrium charge states for tellurium ions (Te, nuclear charge 52), and present a method to estimate the cross sections and rates for ionization and recombination of ions with arbitrary nuclear charge Z and atomic mass number A.
Quantum simulation of non-equilibrium dynamical maps with trapped ions
NASA Astrophysics Data System (ADS)
Schindler, Philipp; Müller, Markus; Nigg, Daniel; Monz, Thomas; Barreiro, Julio; Martinez, Esteban; Hennrich, Markus; Diehl, Sebastian; Zoller, Peter; Blatt, Rainer
2013-03-01
Dynamical maps are central for the understanding of general state transformations of physical systems. Prime examples include classical nonlinear systems undergoing transitions to chaos, or single particle quantum mechanical counterparts showing intriguing phenomena such as dynamical localization. Here, we extend the concept of dynamical maps to an open-system, many-particle context and experimentally explore the stroboscopic dynamics of a complex many-body spin model in a universal quantum simulator using up to five ions. We generate quantum mechanical long range order by an iteration of purely dissipative maps, reveal the characteristic features of a combined coherent and dissipative non-equilibrium evolution, and develop and implement various error detection and reduction techniques that will facilitate the faithful quantum simulation of larger systems.
Protein accumulation in the endoplasmic reticulum as a non-equilibrium phase transition.
Budrikis, Zoe; Costantini, Giulio; La Porta, Caterina A M; Zapperi, Stefano
2014-01-01
Several neurological disorders are associated with the aggregation of aberrant proteins, often localized in intracellular organelles such as the endoplasmic reticulum. Here we study protein aggregation kinetics by mean-field reactions and three dimensional Monte carlo simulations of diffusion-limited aggregation of linear polymers in a confined space, representing the endoplasmic reticulum. By tuning the rates of protein production and degradation, we show that the system undergoes a non-equilibrium phase transition from a physiological phase with little or no polymer accumulation to a pathological phase characterized by persistent polymerization. A combination of external factors accumulating during the lifetime of a patient can thus slightly modify the phase transition control parameters, tipping the balance from a long symptomless lag phase to an accelerated pathological development. The model can be successfully used to interpret experimental data on amyloid-β clearance from the central nervous system. PMID:24722051
Protein accumulation in the endoplasmic reticulum as a non-equilibrium phase transition
Budrikis, Zoe; Costantini, Giulio; La Porta, Caterina A. M.; Zapperi, Stefano
2014-01-01
Several neurological disorders are associated with the aggregation of aberrant proteins, often localized in intracellular organelles such as the endoplasmic reticulum. Here we study protein aggregation kinetics by mean-field reactions and three dimensional Monte carlo simulations of diffusion-limited aggregation of linear polymers in a confined space, representing the endoplasmic reticulum. By tuning the rates of protein production and degradation, we show that the system undergoes a non-equilibrium phase transition from a physiological phase with little or no polymer accumulation to a pathological phase characterized by persistent polymerization. A combination of external factors accumulating during the lifetime of a patient can thus slightly modify the phase transition control parameters, tipping the balance from a long symptomless lag phase to an accelerated pathological development. The model can be successfully used to interpret experimental data on amyloid-β clearance from the central nervous system. PMID:24722051
Non-equilibrium phase transition properties of disordered binary ferromagnetic alloy
NASA Astrophysics Data System (ADS)
Vatansever, Erol; Akinci, Umit; Polat, Hamza
2015-09-01
Non-equilibrium dynamic phase transition features of a disordered binary ferromagnetic alloy consisting of spin- 1 / 2 and spin-1 components under the presence of a time dependent oscillating magnetic field have been analyzed for a two dimensional square lattice. With the help of Glauber-type stochastic process, the kinetic equations of time dependent magnetizations have been derived based on the effective-field theory with single-site correlations. A systematic analysis for the whole range of the concentrations of randomly distributed components as well as other system parameters has been carried out. According to our numerical investigations, the considered system presents unusual thermal and magnetic field behaviors such as the existence of dynamic multi-critical behavior and also boundaries of the coexistence region, where both dynamically ordered and disordered phases overlap, sensitively depends on the studied parameter space.
Non-equilibrium 8π Josephson effect in atomic Kitaev wires
NASA Astrophysics Data System (ADS)
Laflamme, C.; Budich, J. C.; Zoller, P.; Dalmonte, M.
2016-08-01
The identification of fractionalized excitations, such as Majorana quasi-particles, would be a striking signal of the realization of exotic quantum states of matter. While the paramount demonstration of such excitations would be a probe of their non-Abelian statistics via controlled braiding operations, alternative proposals exist that may be easier to access experimentally. Here we identify a signature of Majorana quasi-particles, qualitatively different from the behaviour of a conventional superconductor, which can be detected in cold atom systems using alkaline-earth-like atoms. The system studied is a Kitaev wire interrupted by an extra site, which gives rise to super-exchange coupling between two Majorana-bound states. We show that this system hosts a tunable, non-equilibrium Josephson effect with a characteristic 8π periodicity of the Josephson current. The visibility of the 8π periodicity of the Josephson current is then studied including the effects of dephasing and particle losses.
Non-equilibrium 8π Josephson effect in atomic Kitaev wires
Laflamme, C.; Budich, J. C.; Zoller, P.; Dalmonte, M.
2016-01-01
The identification of fractionalized excitations, such as Majorana quasi-particles, would be a striking signal of the realization of exotic quantum states of matter. While the paramount demonstration of such excitations would be a probe of their non-Abelian statistics via controlled braiding operations, alternative proposals exist that may be easier to access experimentally. Here we identify a signature of Majorana quasi-particles, qualitatively different from the behaviour of a conventional superconductor, which can be detected in cold atom systems using alkaline-earth-like atoms. The system studied is a Kitaev wire interrupted by an extra site, which gives rise to super-exchange coupling between two Majorana-bound states. We show that this system hosts a tunable, non-equilibrium Josephson effect with a characteristic 8π periodicity of the Josephson current. The visibility of the 8π periodicity of the Josephson current is then studied including the effects of dephasing and particle losses. PMID:27481540
Visualizing non-equilibrium lithiation of spinel oxide via in situ transmission electron microscopy
NASA Astrophysics Data System (ADS)
He, Kai; Zhang, Sen; Li, Jing; Yu, Xiqian; Meng, Qingping; Zhu, Yizhou; Hu, Enyuan; Sun, Ke; Yun, Hongseok; Yang, Xiao-Qing; Zhu, Yimei; Gan, Hong; Mo, Yifei; Stach, Eric A.; Murray, Christopher B.; Su, Dong
2016-05-01
Spinel transition metal oxides are important electrode materials for lithium-ion batteries, whose lithiation undergoes a two-step reaction, whereby intercalation and conversion occur in a sequential manner. These two reactions are known to have distinct reaction dynamics, but it is unclear how their kinetics affects the overall electrochemical response. Here we explore the lithiation of nanosized magnetite by employing a strain-sensitive, bright-field scanning transmission electron microscopy approach. This method allows direct, real-time, high-resolution visualization of how lithiation proceeds along specific reaction pathways. We find that the initial intercalation process follows a two-phase reaction sequence, whereas further lithiation leads to the coexistence of three distinct phases within single nanoparticles, which has not been previously reported to the best of our knowledge. We use phase-field theory to model and describe these non-equilibrium reaction pathways, and to directly correlate the observed phase evolution with the battery's discharge performance.
On the non-equilibrium dynamics of cavitation around the underwater projectile in variable motion
NASA Astrophysics Data System (ADS)
Chen, Y.; Lu, C. J.; Li, J.; Chen, X.; Gong, Z. X.
2015-12-01
In this work, the dynamic behavior of the non-equilibrium cavitation occurring around the underwater projectiles navigating with variable speed was numerically and theoretically investigated. The cavity collapse induced by the decelerating motion of the projectiles can be classified into two types: periodic oscillation and damped oscillation. In each type the evolution of the total mass of vapor in cavity are found to have strict correlation with the pressure oscillation in far field. By defining the equivalent radius of cavity, we introduce the specific kinetic energy of collapse and demonstrate that its change-rate is in good agreement with the pressure disturbance. We numerically investigated the influence of angle of attack on the collapse effect. The result shows that when the projectile decelerates, an asymmetric-focusing effect of the pressure induced by collapse occurs on its pressure side. We analytically explained such asymmetric-focusing effect.
Modeling of DNA thermophoresis in dilute solutions using the non-equilibrium thermodynamics approach
NASA Astrophysics Data System (ADS)
Eslamian, Morteza; Saghir, M. Ziad
2012-03-01
Our previous approach on thermodiffusion modeling of dilute polymer solutions is extended to dilute DNA solutions. The model is based on linear non-equilibrium thermodynamics and the concept of Eyring's activation energy of viscous flow to estimate the Soret coefficient in thermophoresis of macromolecules that are not in liquid phase. The net heat of transport of single- and double-stranded DNA molecules, which are in solid state, are replaced by the activation energy of viscous flow of liquid alkanes with comparable molecular weights. The proposed formula is tested against available experimental data and qualitative agreement is observed. For double-stranded DNA molecules, the experimental data are scattered and the model can qualitatively predict the data, whereas for single-stranded DNA experiments in the infinite dilution model, for which the model is prescribed, a very good agreement is observed.
Impurity-tuned non-equilibrium phase transition in a bacterial carpet
NASA Astrophysics Data System (ADS)
Hsiao, Yi-Teng; Wu, Kuan-Ting; Uchida, Nariya; Woon, Wei-Yen
2016-05-01
The effects of impurity on the non-equilibrium phase transition in Vibrio alginolyticus bacterial carpets are investigated through a position-sensitive-diode implemented optical tweezers-microsphere assay. The collective flow increases abruptly as we increase the rotation rate of flagella via Na+ concentration. The effects of impurities on the transition behavior are examined by mixing cells of a wild type strain (VIO5) with cells of a mutant strain (NMB136) in different swimming patterns. For dilute impurities, the transition point is shifted toward higher Na+ concentration. Increasing the impurities' ratio to over 0.25 leads to a significant drop in the collective force, suggesting a partial orientational order with a smaller correlation length.
Non-equilibrium physics and evolution—adaptation, extinction, and ecology: a Key Issues review
NASA Astrophysics Data System (ADS)
Kussell, E.; Vucelja, M.
2014-10-01
Evolutionary dynamics in nature constitute an immensely complex non-equilibrium process. We review the application of physical models of evolution, by focusing on adaptation, extinction, and ecology. In each case, we examine key concepts by working through examples. Adaptation is discussed in the context of bacterial evolution, with a view toward the relationship between growth rates, mutation rates, selection strength, and environmental changes. Extinction dynamics for an isolated population are reviewed, with emphasis on the relation between timescales of extinction, population size, and temporally correlated noise. Ecological models are discussed by focusing on the effect of spatial interspecies interactions on diversity. Connections between physical processes—such as diffusion, turbulence, and localization—and evolutionary phenomena are highlighted.
The Influence of Trapped Ions and Non-equilibrium EDF on Dust Particle Charging
Sukhinin, G. I.; Fedoseev, A. V.; Antipov, S. N.; Petrov, O. F.; Fortov, V. E.
2008-09-07
Dust particles charging in a low-pressure glow discharge was investigated theoretically with the help of model for trapped and free ions coupled with the self-consistent solution of Poisson equation for electric potential. Non-equilibrium (non-Maxwellian) character of electron energy distribution function depending on gas pressure and electric field was also taken into account on the basis of the solution of kinetic Boltzmann equation. The results were compared with the experimental measurements of dust particle charge depending on gas pressure. It was shown that the calculated effective charge, i.e. the difference of the dust particle charge and trapped ion charge, is in a fairly good agreement with the experimental data.
NASA Astrophysics Data System (ADS)
Do, Van-Nam
2014-09-01
We review fundamental aspects of the non-equilibrium Green function method in the simulation of nanometer electronic devices. The method is implemented into our recently developed computer package OPEDEVS to investigate transport properties of electrons in nano-scale devices and low-dimensional materials. Concretely, we present the definition of the four real-time Green functions, the retarded, advanced, lesser and greater functions. Basic relations among these functions and their equations of motion are also presented in detail as the basis for the performance of analytical and numerical calculations. In particular, we review in detail two recursive algorithms, which are implemented in OPEDEVS to solve the Green functions defined in finite-size opened systems and in the surface layer of semi-infinite homogeneous ones. Operation of the package is then illustrated through the simulation of the transport characteristics of a typical semiconductor device structure, the resonant tunneling diodes.
NASA Astrophysics Data System (ADS)
Jamali, Safa; Boromand, Arman; Khani, Shaghayegh; Maia, Joao
2015-12-01
We present in this letter an auxiliary thermostat for non-equilibrium simulations in Dissipative Particle Dynamics based on the Gaussian distribution of particle velocities in the fluid. We demonstrate the ability of the thermostat to maintain the temperature under a wide range of shear rates and dissipative parameters, and to extend the shear rate window accessible by DPD significantly. The effect of proposed method on the viscosity of a DPD fluid is studied which is particularly of interest when the rheological behavior of a complex fluids is subject of DPD simulations. Furthermore, performance of the proposed method is compared to the ones from the well-known Lowe-Andersen scheme in regards to temperature and viscosity measurements.
Role of trap-induced scales in non-equilibrium dynamics of strongly interacting trapped bosons
NASA Astrophysics Data System (ADS)
Dutta, Anirban; Sensarma, Rajdeep; Sengupta, K.
2016-08-01
We use a time-dependent hopping expansion technique to study the non-equilibrium dynamics of strongly interacting bosons in an optical lattice in the presence of a harmonic trap characterized by a force constant K. We show that after a sudden quench of the hopping amplitude J across the superfluid (SF)-Mott insulator (MI) transition, the SF order parameter |{{Δ }\\mathbf{r}}(t)| and the local density fluctuation δ {{n}\\mathbf{r}}(t) exhibit sudden decoherence beyond a trap-induced time scale {{T}0}∼ {{K}-1/2} . We also show that after a slow linear ramp down of J, |{{Δ }\\mathbf{r}}| and the boson defect density {{P}\\mathbf{r}} display a novel non-monotonic spatial profile. Both these phenomena can be explained as consequences of trap-induced time and length scales affecting the dynamics and can be tested by concrete experiments.
Non-equilibrium critical properties of the Ising model on product graphs
NASA Astrophysics Data System (ADS)
Burioni, Raffaella; Corberi, Federico; Vezzani, Alessandro
2010-12-01
We study numerically the non-equilibrium critical properties of the Ising model defined on direct products of graphs, obtained from factor graphs without phase transition (Tc = 0). On this class of product graphs, the Ising model features a finite temperature phase transition, and we find a pattern of scaling behaviors analogous to the one known on regular lattices: observables take a scaling form in terms of a function L(t) of time, with the meaning of a growing length inside which a coherent fractal structure, the critical state, is progressively formed. Computing universal quantities, such as the critical exponents and the limiting fluctuation-dissipation ratio X_\\infty , allows us to comment on the possibility to extend universality concepts to the critical behavior on inhomogeneous substrates.
NASA Astrophysics Data System (ADS)
Qorbani, Khadijeh; Kvamme, Bjørn
2016-04-01
Natural gas hydrates (NGHs) in nature are formed from various hydrate formers (i.e. aqueous, gas, and adsorbed phases). As a result, due to Gibbs phase rule and the combined first and second laws of thermodynamics CH4-hydrate cannot reach thermodynamic equilibrium in real reservoir conditions. CH4 is the dominant component in NGH reservoirs. It is formed as a result of biogenic degradation of biological material in the upper few hundred meters of subsurface. It has been estimated that the amount of fuel-gas reserve in NGHs exceed the total amount of fossil fuel explored until today. Thus, these reservoirs have the potential to satisfy the energy requirements of the future. However, released CH4 from dissociated NGHs could find its way to the atmosphere and it is a far more aggressive greenhouse gas than CO2, even though its life-time is shorter. Lack of reliable field data makes it difficult to predict the production potential, as well as safety of CH4 production from NGHs. Computer simulations can be used as a tool to investigate CH4 production through different scenarios. Most hydrate simulators within academia and industry treat hydrate phase transitions as an equilibrium process and those which employ the kinetic approach utilize simple laboratory data in their models. Furthermore, it is typical to utilize a limited thermodynamic description where only temperature and pressure projections are considered. Another widely used simplification is to assume only a single route for the hydrate phase transitions. The non-equilibrium nature of hydrate indicates a need for proper kinetic models to describe hydrate dissociation and reformation in the reservoir with respect to thermodynamics variables, CH4 mole-fraction, pressure and temperature. The RetrasoCodeBright (RCB) hydrate simulator has previously been extended to model CH4-hydrate dissociation towards CH4 gas and water. CH4-hydrate is added to the RCB data-base as a pseudo mineral. Phase transitions are treated
Thermal Non-equilibrium Revealed by Periodic Pulses of Random Amplitudes in Solar Coronal Loops
NASA Astrophysics Data System (ADS)
Auchère, F.; Froment, C.; Bocchialini, K.; Buchlin, E.; Solomon, J.
2016-08-01
We recently detected variations in extreme ultraviolet intensity in coronal loops repeating with periods of several hours. Models of loops including stratified and quasi-steady heating predict the development of a state of thermal non-equilibrium (TNE): cycles of evaporative upflows at the footpoints followed by falling condensations at the apex. Based on Fourier and wavelet analysis, we demonstrate that the observed periodic signals are indeed not signatures of vibrational modes. Instead, superimposed on the power law expected from the stochastic background emission, the power spectra of the time series exhibit the discrete harmonics and continua expected from periodic trains of pulses of random amplitudes. These characteristics reinforce our earlier interpretation of these pulsations as being aborted TNE cycles.
Entropy analysis on non-equilibrium two-phase flow models
Karwat, H.; Ruan, Y.Q.
1995-09-01
A method of entropy analysis according to the second law of thermodynamics is proposed for the assessment of a class of practical non-equilibrium two-phase flow models. Entropy conditions are derived directly from a local instantaneous formulation for an arbitrary control volume of a structural two-phase fluid, which are finally expressed in terms of the averaged thermodynamic independent variables and their time derivatives as well as the boundary conditions for the volume. On the basis of a widely used thermal-hydraulic system code it is demonstrated with practical examples that entropy production rates in control volumes can be numerically quantified by using the data from the output data files. Entropy analysis using the proposed method is useful in identifying some potential problems in two-phase flow models and predictions as well as in studying the effects of some free parameters in closure relationships.
Non-equilibrium current cumulants and moments with a point-like defect
NASA Astrophysics Data System (ADS)
Mintchev, Mihail; Santoni, Luca; Sorba, Paul
2016-07-01
We derive the exact n-point current expectation values in the Landauer-Büttiker non-equilibrium steady state of a multi terminal system with star graph geometry and a point-like defect localised in the vertex. The current cumulants are extracted from the connected correlation functions and the cumulant generating function is established. We determine the moments, show that the associated moment problem has a unique solution and reconstruct explicitly the corresponding probability distribution. The basic building blocks of this distribution are the probabilities of particle emission and absorption from the heat reservoirs, driving the system away from equilibrium. We derive and analyse in detail these probabilities, showing that they fully describe the quantum transport problem in the system.
Visualizing non-equilibrium lithiation of spinel oxide via in situ transmission electron microscopy.
He, Kai; Zhang, Sen; Li, Jing; Yu, Xiqian; Meng, Qingping; Zhu, Yizhou; Hu, Enyuan; Sun, Ke; Yun, Hongseok; Yang, Xiao-Qing; Zhu, Yimei; Gan, Hong; Mo, Yifei; Stach, Eric A; Murray, Christopher B; Su, Dong
2016-01-01
Spinel transition metal oxides are important electrode materials for lithium-ion batteries, whose lithiation undergoes a two-step reaction, whereby intercalation and conversion occur in a sequential manner. These two reactions are known to have distinct reaction dynamics, but it is unclear how their kinetics affects the overall electrochemical response. Here we explore the lithiation of nanosized magnetite by employing a strain-sensitive, bright-field scanning transmission electron microscopy approach. This method allows direct, real-time, high-resolution visualization of how lithiation proceeds along specific reaction pathways. We find that the initial intercalation process follows a two-phase reaction sequence, whereas further lithiation leads to the coexistence of three distinct phases within single nanoparticles, which has not been previously reported to the best of our knowledge. We use phase-field theory to model and describe these non-equilibrium reaction pathways, and to directly correlate the observed phase evolution with the battery's discharge performance.
Accelerated self-replication under non-equilibrium, periodic energy delivery.
Zhang, Rui; Walker, David A; Grzybowski, Bartosz A; Olvera de la Cruz, Monica
2014-01-01
Self-replication is a remarkable phenomenon in nature that has fascinated scientists for decades. In a self-replicating system, the original units are attracted to a template, which induce their binding. In equilibrium, the energy required to disassemble the newly assembled copy from the mother template is supplied by thermal energy. The possibility of optimizing self-replication was explored by controlling the frequency at which energy is supplied to the system. A model system inspired by a class of light-switchable colloids was considered where light is used to control the interactions. Conditions under which self-replication can be significantly more effective under non-equilibrium, cyclic energy delivery than under equilibrium constant energy conditions were identified. Optimal self-replication does not require constant energy expenditure. Instead, the proper timing at which energy is delivered to the system is an essential controllable parameter to induce high replication rates.
Open Source Radiation Hardened by Design Technology
NASA Technical Reports Server (NTRS)
Shuler, Robert
2016-01-01
The proposed technology allows use of the latest microcircuit technology with lowest power and fastest speed, with minimal delay and engineering costs, through new Radiation Hardened by Design (RHBD) techniques that do not require extensive process characterization, technique evaluation and re-design at each Moore's Law generation. The separation of critical node groups is explicitly parameterized so it can be increased as microcircuit technologies shrink. The technology will be open access to radiation tolerant circuit vendors. INNOVATION: This technology would enhance computation intensive applications such as autonomy, robotics, advanced sensor and tracking processes, as well as low power applications such as wireless sensor networks. OUTCOME / RESULTS: 1) Simulation analysis indicates feasibility. 2)Compact voting latch 65 nanometer test chip designed and submitted for fabrication -7/2016. INFUSION FOR SPACE / EARTH: This technology may be used in any digital integrated circuit in which a high level of resistance to Single Event Upsets is desired, and has the greatest benefit outside low earth orbit where cosmic rays are numerous.
Imploding plasma radiation sources: basic concepts. Memorandum report
Guillory, J.; Davis, J.
1984-07-31
This document is prepared as a briefing aid and technical primer for persons unfamiliar and uninitiated with the theory of imploding plasma radiation sources. It is hoped that it will prove helpful in introducing the basic physics concepts of these sources and in presenting these concepts to newcomers and potential users.
Interactions of Virus Like Particles in Equilibrium and Non-equilibrium Systems
NASA Astrophysics Data System (ADS)
Lin, Hsiang-Ku
This thesis summarizes my Ph.D. research on the interactions of virus like particles in equilibrium and non-equilibrium biological systems. In the equilibrium system, we studied the fluctuation-induced forces between inclusions in a fluid membrane. We developed an exact method to calculate thermal Casimir forces between inclusions of arbitrary shapes and separation, embedded in a fluid membrane whose fluctuations are governed by the combined action of surface tension, bending modulus, and Gaussian rigidity. Each objects shape and mechanical properties enter only through a characteristic matrix, a static analog of the scattering matrix. We calculate the Casimir interaction between two elastic disks embedded in a membrane. In particular, we find that at short separations the interaction is strong and independent of surface tension. In the non-equilibrium system, we studied the transport and deposition dynamics of colloids in saturated porous media under un-favorable filtering conditions. As an alternative to traditional convection-diffusion or more detailed numerical models, we consider a mean-field description in which the attachment and detachment processes are characterized by an entire spectrum of rate constants, ranging from shallow traps which mostly account for hydrodynamic dispersivity, all the way to the permanent traps associated with physical straining. The model has an analytical solution which allows analysis of its properties including the long time asymptotic behavior and the profile of the deposition curves. Furthermore, the model gives rise to a filtering front whose structure, stability and propagation velocity are examined. Based on these results, we propose an experimental protocol to determine the parameters of the model.
Error suppression and error correction in adiabatic quantum computation: non-equilibrium dynamics
NASA Astrophysics Data System (ADS)
Sarovar, Mohan; Young, Kevin C.
2013-12-01
While adiabatic quantum computing (AQC) has some robustness to noise and decoherence, it is widely believed that encoding, error suppression and error correction will be required to scale AQC to large problem sizes. Previous works have established at least two different techniques for error suppression in AQC. In this paper we derive a model for describing the dynamics of encoded AQC and show that previous constructions for error suppression can be unified with this dynamical model. In addition, the model clarifies the mechanisms of error suppression and allows the identification of its weaknesses. In the second half of the paper, we utilize our description of non-equilibrium dynamics in encoded AQC to construct methods for error correction in AQC by cooling local degrees of freedom (qubits). While this is shown to be possible in principle, we also identify the key challenge to this approach: the requirement of high-weight Hamiltonians. Finally, we use our dynamical model to perform a simplified thermal stability analysis of concatenated-stabilizer-code encoded many-body systems for AQC or quantum memories. This work is a companion paper to ‘Error suppression and error correction in adiabatic quantum computation: techniques and challenges (2013 Phys. Rev. X 3 041013)’, which provides a quantum information perspective on the techniques and limitations of error suppression and correction in AQC. In this paper we couch the same results within a dynamical framework, which allows for a detailed analysis of the non-equilibrium dynamics of error suppression and correction in encoded AQC.
Non-equilibrium steady states in the Klein-Gordon theory
NASA Astrophysics Data System (ADS)
Doyon, Benjamin; Lucas, Andrew; Schalm, Koenraad; Bhaseen, M. J.
2015-03-01
We construct non-equilibrium steady states in the Klein-Gordon theory in arbitrary space dimension d following a local quench. We consider the approach where two independently thermalized semi-infinite systems, with temperatures {{T}L} and {{T}R}, are connected along a d-1-dimensional hypersurface. A current-carrying steady state, described by thermally distributed modes with temperatures {{T}L} and {{T}R} for left and right-moving modes, respectively, emerges at late times. The non-equilibrium density matrix is the exponential of a non-local conserved charge. We obtain exact results for the average energy current and the complete distribution of energy current fluctuations. The latter shows that the long-time energy transfer can be described by a continuum of independent Poisson processes, for which we provide the exact weights. We further describe the full time evolution of local observables following the quench. Averages of generic local observables, including the stress-energy tensor, approach the steady state with a power-law in time, where the exponent depends on the initial conditions at the connection hypersurface. We describe boundary conditions and special operators for which the steady state is reached instantaneously on the connection hypersurface. A semiclassical analysis of freely propagating modes yields the average energy current at large distances and late times. We conclude by comparing and contrasting our findings with results for interacting theories and provide an estimate for the timescale governing the crossover to hydrodynamics. As a modification of our Klein-Gordon analysis we also include exact results for free Dirac fermions.
NON-EQUILIBRIUM THERMODYNAMIC PROCESSES: SPACE PLASMAS AND THE INNER HELIOSHEATH
Livadiotis, G.; McComas, D. J.
2012-04-10
Recently, empirical kappa distribution, commonly used to describe non-equilibrium systems like space plasmas, has been connected with non-extensive statistical mechanics. Here we show how a consistent definition of the temperature and pressure is developed for stationary states out of thermal equilibrium, so that the familiar ideal gas state equation still holds. In addition to the classical triplet of temperature, pressure, and density, this generalization requires the kappa index as a fourth independent thermodynamic variable that characterizes the non-equilibrium stationary states. All four of these thermodynamic variables have key roles in describing the governing thermodynamical processes and transitions in space plasmas. We introduce a novel characterization of isothermal and isobaric processes that describe a system's transition into different stationary states by varying the kappa index. In addition, we show how the variation of temperature or/and pressure can occur through an 'iso-q' process, in which the system remains in a fixed stationary state (fixed kappa index). These processes have been detected in the proton plasma in the inner heliosheath via specialized data analysis of energetic neutral atom (ENA) observations from Interstellar Boundary Explorer. In particular, we find that the temperature is highly correlated with (1) kappa, asymptotically related to isothermal ({approx}1,000,000 K) and iso-q ({kappa} {approx} 1.7) processes; and (2) density, related to an isobaric process, which separates the 'Ribbon', P Almost-Equal-To 3.2 pdyn cm{sup -2}, from the globally distributed ENA flux, P Almost-Equal-To 2 pdyn cm{sup -2}.
Non-Equilibrium Zeldovich-Von Neumann-Doring Theory and Reactive Flow Modeling of Detonation
Tarver, C M; Forbes, J W; Urtiew, P A
2002-05-02
This paper discusses the Non-Equilibrium Zeldovich - von Neumann - Doring (NEZND) theory of self-sustaining detonation waves and the Ignition and Growth reactive flow model of shock initiation and detonation wave propagation in solid explosives. The NEZND theory identified the non-equilibrium excitation processes that precede and follow the exothermic decomposition of a large high explosive molecule into several small reaction product molecules. The thermal energy deposited by the leading shock wave must be distributed to the vibrational modes of the explosive molecule before chemical reactions can occur. The induction time for the onset of the initial endothermic reactions can be calculated using high pressure, high temperature transition state theory. Since the chemical energy is released well behind the leading shock front of a detonation wave, a physical mechanism is required for this chemical energy to reinforce the leading shock front and maintain its overall constant velocity. This mechanism is the amplification of pressure wavelets in the reaction zone by the process of de-excitation of the initially highly vibrationally excited reaction product molecules. This process leads to the development of the three-dimensional structure of detonation waves observed for all explosives. For practical predictions of shock initiation and detonation in hydrodynamic codes, phenomenological reactive flow models have been developed. The Ignition and Growth reactive flow model of shock initiation and detonation in solid explosives has been very successful in describing the overall flow measured by embedded gauges and laser interferometry. This reactive flow model uses pressure and compression dependent reaction rates, because time resolved experimental temperature data is not yet available. Since all chemical reaction rates are ultimately controlled by temperature, the next generation of reactive flow models will use temperature dependent reaction rates. Progress on a
NASA Astrophysics Data System (ADS)
Lu, X.; Naidis, G. V.; Laroussi, M.; Reuter, S.; Graves, D. B.; Ostrikov, K.
2016-05-01
Non-equilibrium atmospheric-pressure plasmas have recently become a topical area of research owing to their diverse applications in health care and medicine, environmental remediation and pollution control, materials processing, electrochemistry, nanotechnology and other fields. This review focuses on the reactive electrons and ionic, atomic, molecular, and radical species that are produced in these plasmas and then transported from the point of generation to the point of interaction with the material, medium, living cells or tissues being processed. The most important mechanisms of generation and transport of the key species in the plasmas of atmospheric-pressure plasma jets and other non-equilibrium atmospheric-pressure plasmas are introduced and examined from the viewpoint of their applications in plasma hygiene and medicine and other relevant fields. Sophisticated high-precision, time-resolved plasma diagnostics approaches and techniques are presented and their applications to monitor the reactive species and plasma dynamics in the plasma jets and other discharges, both in the gas phase and during the plasma interaction with liquid media, are critically reviewed. The large amount of experimental data is supported by the theoretical models of reactive species generation and transport in the plasmas, surrounding gaseous environments, and plasma interaction with liquid media. These models are presented and their limitations are discussed. Special attention is paid to biological effects of the plasma-generated reactive oxygen and nitrogen (and some other) species in basic biological processes such as cell metabolism, proliferation, survival, etc. as well as plasma applications in bacterial inactivation, wound healing, cancer treatment and some others. Challenges and opportunities for theoretical and experimental research are discussed and the authors' vision for the emerging convergence trends across several disciplines and application domains is presented to
Future radiation sources and identification of irradiated foods
Brynjolfsson, A. )
1989-07-01
Two major questions regarding irradiation that are raised today are: (1) Which sources should be used for irradiating food and (2) How can irradiated foods be identified This article considers both questions. After briefly mentioning a few of the historical stepping stones in the development of radiation sources, present and future radiation sources are discussed. Next the changes in foods caused by irradiation are considered. These changes are extremely small-so minor in fact that it is difficult to detect if the food has been irradiated. Still, these are several detection methods available, and this article describes them.
Spontaneous Raman scattering as a high resolution XUV radiation source
NASA Technical Reports Server (NTRS)
Rothenberg, J. E.; Young, J. F.; Harris, S. E.
1983-01-01
A type of high resolution XUV radiation source is described which is based upon spontaneous anti-Stokes scattering of tunable incident laser radiation from atoms excited to metastable levels. The theory of the source is summarized and two sets of experiments using He (1s2s)(1)S atoms, produced in a cw hollow cathode and in a pulsed high power microwave discharge, are discussed. The radiation source is used to examine transitions originating from the 3p(6) shell of potassium. The observed features include four previously unreported absorption lines and several sharp interferences of closely spaced autoionizing lines. A source linewidth of about 1.9 cm(-1) at 185,000 cm(-1) is demonstrated.
Salazar, Ramon B. E-mail: hilatikh@purdue.edu; Appenzeller, Joerg; Ilatikhameneh, Hesameddin E-mail: hilatikh@purdue.edu; Rahman, Rajib; Klimeck, Gerhard
2015-10-28
A new compact modeling approach is presented which describes the full current-voltage (I-V) characteristic of high-performance (aggressively scaled-down) tunneling field-effect-transistors (TFETs) based on homojunction direct-bandgap semiconductors. The model is based on an analytic description of two key features, which capture the main physical phenomena related to TFETs: (1) the potential profile from source to channel and (2) the elliptic curvature of the complex bands in the bandgap region. It is proposed to use 1D Poisson's equations in the source and the channel to describe the potential profile in homojunction TFETs. This allows to quantify the impact of source/drain doping on device performance, an aspect usually ignored in TFET modeling but highly relevant in ultra-scaled devices. The compact model is validated by comparison with state-of-the-art quantum transport simulations using a 3D full band atomistic approach based on non-equilibrium Green's functions. It is shown that the model reproduces with good accuracy the data obtained from the simulations in all regions of operation: the on/off states and the n/p branches of conduction. This approach allows calculation of energy-dependent band-to-band tunneling currents in TFETs, a feature that allows gaining deep insights into the underlying device physics. The simplicity and accuracy of the approach provide a powerful tool to explore in a quantitatively manner how a wide variety of parameters (material-, size-, and/or geometry-dependent) impact the TFET performance under any bias conditions. The proposed model presents thus a practical complement to computationally expensive simulations such as the 3D NEGF approach.
New high power coherent radiation sources. Memorandum report
Sprangle, P.; Coffey, T.
1984-01-09
In recent years, there has been considerable renewed interest in the development of novel devices for the production of high power coherent electromagnetic radiation. This interest has been motivated largely by the realization that, with existing technology, certain processes utilizing relativistic electron beams can produce coherent electromagnetic radiation at power levels far in excess of those achieved by conventional electron devices. This paper will review the current status of this rapidly developing field, with emphasis on two generic devices. The major thrust in the recent development of electron beam driven radiation sources has been directed towards achieving shorter wavelengths, greater power and higher efficiencies. Shortly after the development of such successful sources as the magnetron, kylstron and various traveling wave devices, it became clear that, in their original form, they were limited in their ability to produce high levels of radiation efficiently at short wavelengths. To circumvent the inherent limitations of these conventional coherent radiation sources, many new concepts and mechanisms, as well as variations on conventional concepts, were proposed. This paper is concerned primarily with two devices which are, relatively speaking, newcomers to the list of coherent classical radiation sources. They are the free electron laser and the cyclotron resonance maser (CRM); one well known type of CRM is the gyrotron.
A capillary discharge plasma source of intense VUV radiation
Sobel'man, Igor I; Shevelko, A P; Yakushev, O F; Knight, L V; Turley, R S
2003-01-31
The results of investigation of a capillary discharge plasma, used as a source of intense VUV radiation and soft X-rays, are presented. The plasma was generated during the discharge of low-inductance condensers in a gas-filled ceramic capillary. Intense line radiation was observed in a broad spectral range (30-400 A) in various gases (CO{sub 2}, Ne, Ar, Kr, Xe). The absolute radiation yield for the xenon discharge was {approx}5 mJ (2{pi} sr){sup -1} pulse{sup -1} within a spectral band of width 9 A at 135 A. Such a radiation source can be used for various practical applications, such as EUV projection lithography, microscopy of biological objects in a 'water window', reflectometry, etc. (special issue devoted to the 80th anniversary of academician n g basov's birth)
NASA Astrophysics Data System (ADS)
Welch, Kyle; Liebman-Pelaez, Alexander; Corwin, Eric
Equilibrium statistical mechanics is traditionally limited to thermal systems. Can it be applied to athermal, non-equilibrium systems that nonetheless satisfy the basic criteria of steady-state chaos and isotropy? We answer this question using a macroscopic system of chaotic surface waves which is, by all measures, non-equilibrium. The waves are generated in a dish of water that is vertically oscillated above a critical amplitude. We have constructed a rheometer that actively measures the drag imparted by the waves on a buoyant particle, a quantity entirely divorced in origin from the drag imparted by the fluid in which the particle floats. We also perform a separate, passive measurement, extracting a diffusion constant and effective temperature. Having directly measured all three properties (temperature, diffusion constant, and drag coefficient) we go on to show that our macroscopic, non-equilibrium case is wholly consistent with the Einstein relation, a classic result for equilibrium thermal systems.
Zhang, Le; Luo, Feng; Xu, Ruina; Jiang, Peixue; Liu, Huihai
2014-12-31
The heat transfer and fluid transport of supercritical CO2 in enhanced geothermal system (EGS) is studied numerically with local thermal non-equilibrium model, which accounts for the temperature difference between solid matrix and fluid components in porous media and uses two energy equations to describe heat transfer in the solid matrix and in the fluid, respectively. As compared with the previous results of our research group, the effect of local thermal non-equilibrium mainly depends on the volumetric heat transfer coefficient ah, which has a significant effect on the production temperature at reservoir outlet and thermal breakthrough time. The uniformity of volumetricmore » heat transfer coefficient ah has little influence on the thermal breakthrough time, but the temperature difference become more obvious with time after thermal breakthrough with this simulation model. The thermal breakthrough time reduces and the effect of local thermal non-equilibrium becomes significant with decreasing ah.« less
A Device for Search of Gamma-Radiation Intensive Sources at the Radiation Accident Condition
Batiy, Valeriy; Klyuchnykov, A; Kochnev, N; Rudko, Vladimir; shcherbin, vladimir; Yegorov, V; Schmieman, Eric A.
2005-08-08
The procedure designed for measuring angular distributions of gamma radiation and for search of gamma radiation intensive sources is described. It is based on application of the original multidetector device ShD-1, for measuring an angular distribution in a complete solid angle (4 pi). The calibration results and data on the angular distributions of intensity of gamma radiation at the roof of Chornobyl NPP ''Shelter'' are presented.
Inertial confinement fusion method producing line source radiation fluence
Rose, Ronald P.
1984-01-01
An inertial confinement fusion method in which target pellets are imploded in sequence by laser light beams or other energy beams at an implosion site which is variable between pellet implosions along a line. The effect of the variability in position of the implosion site along a line is to distribute the radiation fluence in surrounding reactor components as a line source of radiation would do, thereby permitting the utilization of cylindrical geometry in the design of the reactor and internal components.
Nagarajan, Ramanathan
2015-07-01
Micelles generated in water from most amphiphilic block copolymers are widely recognized to be non-equilibrium structures. Typically, the micelles are prepared by a kinetic process, first allowing molecular scale dissolution of the block copolymer in a common solvent that likes both the blocks and then gradually replacing the common solvent by water to promote the hydrophobic blocks to aggregate and create the micelles. The non-equilibrium nature of the micelle originates from the fact that dynamic exchange between the block copolymer molecules in the micelle and the singly dispersed block copolymer molecules in water is suppressed, because of the glassy nature of the core forming polymer block and/or its very large hydrophobicity. Although most amphiphilic block copolymers generate such non-equilibrium micelles, no theoretical approach to a priori predict the micelle characteristics currently exists. In this work, we propose a predictive approach for non-equilibrium micelles with glassy cores by applying the equilibrium theory of micelles in two steps. In the first, we calculate the properties of micelles formed in the mixed solvent while true equilibrium prevails, until the micelle core becomes glassy. In the second step, we freeze the micelle aggregation number at this glassy state and calculate the corona dimension from the equilibrium theory of micelles. The condition when the micelle core becomes glassy is independently determined from a statistical thermodynamic treatment of diluent effect on polymer glass transition temperature. The predictions based on this "non-equilibrium" model compare reasonably well with experimental data for polystyrene-polyethylene oxide diblock copolymer, which is the most extensively studied system in the literature. In contrast, the application of the equilibrium model to describe such a system significantly overpredicts the micelle core and corona dimensions and the aggregation number. The non-equilibrium model suggests ways to
[Risks associated to ionizing radiation from natural sources].
Laurier, Dominique; Gay, Didier
2015-01-01
This article presents an overview of current knowledge about natural sources of radiation exposure and potential associated health risks. Natural radioactivity constitutes the main source of exposure to ionizing radiation of the French and world population. Exposure is both external (telluric and cosmic rays) and internal (radon inhalation and ingestion of radionuclides from food and drinking water). It varies according to altitude, geology, and individual way of life (housing, food habits). Epidemiological studies demonstrated an excess risk of lung cancer associated to domestic radon exposure, ranking radon at the second place of known lung cancer risk factors after smoking. Data currently available do not allow concluding to risks associated to other natural sources of exposure to ionizing radiation. PMID:25842437
Double planar wire array as a compact plasma radiation source
Kantsyrev, V. L.; Safronova, A. S.; Esaulov, A. A.; Williamson, K. M.; Yilmaz, M. F.; Shrestha, I.; Ouart, N. D.; Osborne, G. C.; Rudakov, L. I.; Chuvatin, A. S.; Coverdale, C. A.; Deeney, C.
2008-03-15
Magnetically compressed plasmas initiated by a double planar wire array (DPWA) are efficient radiation sources. The two rows in a DPWA implode independently and then merge together at stagnation producing soft x-ray yields and powers of up to 11.5 kJ/cm and more than 0.4 TW/cm, higher than other planar arrays or low wire-number cylindrical arrays on the 1 MA Zebra generator. DPWA, where precursors form in two stages, produce a shaped radiation pulse and radiate more energy in the main burst than estimates of implosion kinetic energy. High radiation efficiency, compact size (as small as 3-5 mm wide), and pulse shaping show that the DPWA is a potential candidate for ICF and radiation physics research.
Producing terahertz coherent synchrotron radiation at the Hefei Light Source
NASA Astrophysics Data System (ADS)
Xu, De-Rong; Xu, Hong-Liang; Shao, Yan
2015-07-01
This paper theoretically proves that an electron storage ring can generate coherent radiation in the THz region using a quick kicker magnet and an AC sextupole magnet. When the vertical chromaticity is modulated by the AC sextupole magnet, the vertical beam collective motion excited by the kicker produces a wavy spatial structure after a number of longitudinal oscillation periods. The radiation spectral distribution was calculated from the wavy bunch parameters at the Hefei Light Source (HLS). When the electron energy is reduced to 400 MeV, extremely strong coherent synchrotron radiation (CSR) at 0.115 THz should be produced. Supported by National Natural Science Foundation of China (11375176)
Astrophysical Ionizing Radiation Sources and Life on Earth
NASA Astrophysics Data System (ADS)
Thomas, Brian
2013-04-01
Astrophysical sources of ionizing radiation have been recognized as a potential threat to life on Earth, primarily through long-term depletion of stratospheric ozone, leading to greatly increased solar ultraviolet (UV) irradiance at the surface. It has been suggested that a gamma-ray burst, in particular, may have initiated the late Ordovician mass extinction - one of the ``big five'' known extinctions. I will describe the atmospheric impacts of ionizing radiation events and discuss estimates of biological damage under a severely depleted ozone layer. In particular, I will describe new and on-going work to quantify the impact of ionizing radiation events on primary producers in Earth's oceans.
Kreula, J M; Clark, S R; Jaksch, D
2016-01-01
We propose a non-linear, hybrid quantum-classical scheme for simulating non-equilibrium dynamics of strongly correlated fermions described by the Hubbard model in a Bethe lattice in the thermodynamic limit. Our scheme implements non-equilibrium dynamical mean field theory (DMFT) and uses a digital quantum simulator to solve a quantum impurity problem whose parameters are iterated to self-consistency via a classically computed feedback loop where quantum gate errors can be partly accounted for. We analyse the performance of the scheme in an example case.
Kreula, J. M.; Clark, S. R.; Jaksch, D.
2016-01-01
We propose a non-linear, hybrid quantum-classical scheme for simulating non-equilibrium dynamics of strongly correlated fermions described by the Hubbard model in a Bethe lattice in the thermodynamic limit. Our scheme implements non-equilibrium dynamical mean field theory (DMFT) and uses a digital quantum simulator to solve a quantum impurity problem whose parameters are iterated to self-consistency via a classically computed feedback loop where quantum gate errors can be partly accounted for. We analyse the performance of the scheme in an example case. PMID:27609673
Kreula, J M; Clark, S R; Jaksch, D
2016-01-01
We propose a non-linear, hybrid quantum-classical scheme for simulating non-equilibrium dynamics of strongly correlated fermions described by the Hubbard model in a Bethe lattice in the thermodynamic limit. Our scheme implements non-equilibrium dynamical mean field theory (DMFT) and uses a digital quantum simulator to solve a quantum impurity problem whose parameters are iterated to self-consistency via a classically computed feedback loop where quantum gate errors can be partly accounted for. We analyse the performance of the scheme in an example case. PMID:27609673
NASA Astrophysics Data System (ADS)
Kreula, J. M.; Clark, S. R.; Jaksch, D.
2016-09-01
We propose a non-linear, hybrid quantum-classical scheme for simulating non-equilibrium dynamics of strongly correlated fermions described by the Hubbard model in a Bethe lattice in the thermodynamic limit. Our scheme implements non-equilibrium dynamical mean field theory (DMFT) and uses a digital quantum simulator to solve a quantum impurity problem whose parameters are iterated to self-consistency via a classically computed feedback loop where quantum gate errors can be partly accounted for. We analyse the performance of the scheme in an example case.
NASA Astrophysics Data System (ADS)
Andreozzi, Laura; Giordano, Marco; Leporini, Dino; Tosi, Mario
2007-04-01
This special issue of Journal of Physics: Condensed Matter presents the Proceedings of the Fourh Workshop on Non-Equilibrium Phenomena in Supercooled Fluids, Glasses and Amorphous Materials, held in Pisa from 17-22 September 2006. This was the fourth of a series of workshops on this theme started in 1995 as a joint initiative of the Università di Pisa and the Scuola Normale Superiore. The 2006 edition was attended by about 200 participants from Europe, Asia and the Americas. As for the earlier workshops, the main objective was to bring together scientists from different areas of science, technology and engineering, to comparatively discuss experimental facts and theoretical predictions on the dynamical processes that occur in supercooled fluids and other disordered materials in non-equilibrium states. The underlying conceptual unity of the field provides a common background for the scientific community working in its various areas. In this edition the number of sessions was increased to cover a wider range of topics of general and current interest, in a larger number of stimulating lectures. The core of the workshop was a set of general lectures followed by more specific presentations on current issues in the main areas of the field. The sessions were in sequence devoted to: non-equilibrium dynamics, aging and secondary relaxations, biomaterials, polyamorphism and water, polymer dynamics I, complex systems, pressure-temperature scaling, thin films, nanometre length-scale studies, folded states of proteins and polymer crystals, theoretical aspects and energy landscape approaches, relaxation and heterogeneous dynamics, rheology in fluids and entangled polymers, biopolymers, and polymer dynamics II. We thank the session chairmen and all speakers for the high quality of their contributions. The structure of this issue of the proceedings follows the sequence of the oral presentations in the workshop, complemented by some papers selected from the poster sessions. Two
Theory of non-equilibrium force measurements involving deformable drops and bubbles.
Chan, Derek Y C; Klaseboer, Evert; Manica, Rogerio
2011-07-11
Over the past decade, direct force measurements using the Atomic Force Microscope (AFM) have been extended to study non-equilibrium interactions. Perhaps the more scientifically interesting and technically challenging of such studies involved deformable drops and bubbles in relative motion. The scientific interest stems from the rich complexity that arises from the combination of separation dependent surface forces such as Van der Waals, electrical double layer and steric interactions with velocity dependent forces from hydrodynamic interactions. Moreover the effects of these forces also depend on the deformations of the surfaces of the drops and bubbles that alter local conditions on the nanometer scale, with deformations that can extend over micrometers. Because of incompressibility, effects of such deformations are strongly influenced by small changes of the sizes of the drops and bubbles that may be in the millimeter range. Our focus is on interactions between emulsion drops and bubbles at around 100 μm size range. At the typical velocities in dynamic force measurements with the AFM which span the range of Brownian velocities of such emulsions, the ratio of hydrodynamic force to surface tension force, as characterized by the capillary number, is ~10(-6) or smaller, which poses challenges to modeling using direct numerical simulations. However, the qualitative and quantitative features of the dynamic forces between interacting drops and bubbles are sensitive to the detailed space and time-dependent deformations. It is this dynamic coupling between forces and deformations that requires a detailed quantitative theoretical framework to help interpret experimental measurements. Theories that do not treat forces and deformations in a consistent way simply will not have much predictive power. The technical challenges of undertaking force measurements are substantial. These range from generating drop and bubble of the appropriate size range to controlling the
Chemical equilibrium and non-equilibrium inviscid flow computations using a centered scheme
NASA Astrophysics Data System (ADS)
Vos, J. B.; Bergman, C. M.
Within the framework of the collaboration between IMHEF and CERFACS a 2D Inviscid Flow solver for Hypersonic flows has been developed. The Euler equations are discretized in space on a structured mesh using the Finite Volume method with centered differences. The resulting system of ordinary differential equations is integrated in time using the explicit Runge Kutta scheme. Artificial dissipation terms are added to damp odd/even oscillations allowed for by centered space differences, and to damp spurious oscillations near discontinuities. External shock waves in the flow field are treated by a shock fitting procedure, while (weaker) internal shock waves are captured by the numerical scheme. A complete description of the numerical method can be found in [1]. The strong shock waves present in hypersonic flows give rise to high temperatures directly behind the shock wave, which may result into the dissociation of air. This is a process which costs energy, hence temperatures in the flow field will be reduced. Air dissociation can be modelled on different levels, which depend on the ratio of the characteristic time scales of the flow and the chemistry. If the characteristic time scale of the chemistry is much smaller than that of the flow, it can be assumed that the flow is in chemical equilibrium, i.e. chemical reactions are taking place, but the production of a chemical species is balanced by its destruction. The other limit is that the chemistry time scale is much smaller than that of the flow, hence no chemical reactions are taking place. The chemistry is frozen, and the air is treated as a thermally perfect gas. If the time scales are of the same order of magnitude the flow is in chemical non-equilibrium. These three levels of modelling have been included in the Euler solver. Incorporation of equilibrium and frozen chemistry is straightforward for the centered scheme described above, since only the relation which connects the pressure to the density and total energy
MCNP model for the many KE-Basin radiation sources
Rittmann, P.D.
1997-05-21
This document presents a model for the location and strength of radiation sources in the accessible areas of KE-Basin which agrees well with data taken on a regular grid in September of 1996. This modelling work was requested to support dose rate reduction efforts in KE-Basin. Anticipated fuel removal activities require lower dose rates to minimize annual dose to workers. With this model, the effects of component cleanup or removal can be estimated in advance to evaluate their effectiveness. In addition, the sources contributing most to the radiation fields in a given location can be identified and dealt with.
Equilibrium and non-equilibrium properties of finite-volume crystallites
NASA Astrophysics Data System (ADS)
Degawa, Masashi
Finite volume effects on equilibrium and non-equilibrium properties of nano-crystallites are studied theoretically and compared to both experiment and simulation. When a system is isolated or its size is small compared to the correlation length, all equilibrium and close-to-equilibrium properties will depend on the system boundary condition. Specifically for solid nano-crystallites, their finite size introduces global curvature to the system, which alters its equilibrium properties compared to the thermodynamic limit. Also such global curvature leads to capillary-induced morphology changes of the surface. Interesting dynamics can arise when the crystallite is supported on a substrate, with crossovers of the dominant driving force from the capillary force and crystallite-substrate interactions. To address these questions, we introduce thermodynamic functions for the boundary conditions, which can be derived from microscopic models. For nano-crystallites, the boundary is the surface (including interfaces), the thermodynamic description is based on the steps that define the shape of the surface, and the underlying microscopic model includes kinks. The global curvature of the surface introduces metastable states with different shapes governed by a constant of integration of the extra boundary condition, which we call the shape parameter c. The discrete height of the steps introduces transition states in between the metastable states, and the lowest energy accessible structure (energy barrier less 10k BT) as a function of the volume has been determined. The dynamics of nano-crystallites as they relax from a non-equilibrium structure is described quantitatively in terms of the motion of steps in both capillary-induced and interface-boundary-induced regimes. The step-edge fluctuations of the top facet are also influenced by global curvature and volume conservation and the effect yields different dynamic scaling exponents from a pure 1D system. Theoretical results are
Smart material-based radiation sources
NASA Astrophysics Data System (ADS)
Kovaleski, Scott
2014-10-01
From sensors to power harvesters, the unique properties of smart materials have been exploited in numerous ways to enable new applications and reduce the size of many useful devices. Smart materials are defined as materials whose properties can be changed in a controlled and often reversible fashion by use of external stimuli, such as electric and magnetic fields, temperature, or humidity. Smart materials have been used to make acceleration sensors that are ubiquitous in mobile phones, to make highly accurate frequency standards, to make unprecedentedly small actuators and motors, to seal and reduce friction of rotating shafts, and to generate power by conversion of either kinetic or thermal energy to electrical energy. The number of useful devices enabled by smart materials is large and continues to grow. Smart materials can also be used to generate plasmas and accelerate particles at small scales. The materials discussed in this talk are from non-centrosymmetric crystalline classes including piezoelectric, pyroelectric, and ferroelectric materials, which produce large electric fields in response to external stimuli such as applied electric fields or thermal energy. First, the use of ferroelectric, pyroelectric and piezoelectric materials for plasma generation and particle acceleration will be reviewed. The talk will then focus on the use of piezoelectric materials at the University of Missouri to construct plasma sources and electrostatic accelerators for applications including space propulsion, x-ray imaging, and neutron production. The basic concepts of piezoelectric transformers, which are analogous to conventional magnetic transformers, will be discussed, along with results from experiments over the last decade to produce micro-thrusters for space propulsion and particle accelerators for x-ray and neutron production. Support from ONR, AFOSR, and LANL.
Wexler, Adam D; Drusová, Sandra; Woisetschläger, Jakob; Fuchs, Elmar C
2016-06-28
In this experiment liquid water is subject to an inhomogeneous electric field (∇(2)Ea≈ 10(10) V m(2)) using a high voltage (20 kV) point-plane electrode system. Using interferometry it was found that the application of a strong electric field gradient to water generates local changes in the refractive index of the liquid, polarizes the surface and creates a downward moving electro-convective jet. A maximum temperature difference of 1 °C is measured in the immediate vicinity of the point electrode. Raman spectroscopy performed on water reveals an enhancement of the vibrational collective modes (3250 cm(-1)) as well as an increase in the local mode (3490 cm(-1)) energy. This bimodal enhancement indicates that the spectral changes are not due to temperature changes. The intense field gradient thus establishes an excited subpopulation of vibrational oscillators far from thermal equilibrium. Delocalization of the collective vibrational mode spatially expands this excited population beyond the microscale. Hindered rotational freedom due to electric field pinning of molecular dipoles retards the heat flow and generates a chemical potential gradient. These changes are responsible for the observed changes in the refractive index and temperature. It is demonstrated that polar liquids can thus support local non-equilibrium thermodynamic transient states critical to biochemical and environmental processes. PMID:27253197
NASA Astrophysics Data System (ADS)
Wheeler Richard, Dean R.; Rowley, L.
Non-equilibrium molecular dynamics (NEMD) with isobaric and isokinetic controls were used to simulate the shear viscosity for binary mixtures of water, methanol and acetone, and for ternary mixtures. In all, 22 different liquid composition points were simulated at 298.15 K and 0.1 MPa. A new set of acetone potential parameters was developed, while slight variants to existing water and methanol models were used. Long range Coulombic interactions were computed with the Ewald sum adapted to Lees-Edwards boundary conditions as formulated in Wheeler, D. R., Fuller, N. G., and Rowley, R. L., 1997, Molec. Phys., 92, 55. The attractive (dispersive) part of the Lennard-Jones (LJ) interactions also was handled by a lattice sum. A hybrid mixing rule was used for the LJ cross interactions. Viscosities extrapolated to zero shear compared well with experimental results, having a mean absolute error of 14% and no errors greater than 30%. Although the simulations successfully predicted viscosity maxima for mixtures high in water content, the peak heights tended to be too low, probably due to the limitations of the water model. The results suggest that NEMD may be a viable means of estimating viscosities for polar liquid mixtures with an unrestricted number of components.
Numerical solution of 2D wet steam flow with non-equilibrium condensation and real thermodynamics
Hric, V.; Halama, J.
2015-03-10
An approach to modeling of wet steam flow with non-equilibrium condensation phenomenon is presented. The first part of our flow model is homogeneous Euler system of transport equations for mass, momentum and total energy of wet steam (mixture). The additional second part describes liquid phase via non-homogeneous system of transport equations for moments of droplets number distribution function and relies on corrected classical nucleation theory. Moment equations are closed by linearization of droplet growth rate model. All necessary relations for thermodynamic properties of steam are provided by IAPWS set of equations. However, properties of condensate are simply modeled by liquid saturation data. Two real equations of state are implemented. Recently developed CFD formulation for entropy (does not require iteration process) and so-called IAPWS special gas equation for Helmholtz energy (one iteration loop is necessary). Flow model is validated on converging-diverging supersonic nozzle with Barschdorff geometry. Simulations were performed by in-house CFD code based on finite volume method and stiff character of equations was solved by symmetrical time operator splitting. Achieved results satisfactorily agreed with experimental data.
Non-equilibrium molecular dynamics simulation of the unstirred layer in the osmotically driven flow
NASA Astrophysics Data System (ADS)
Konno, Keito; Itano, Tomoaki; Seki, Masako
2015-11-01
We studied the solvent flows driven by the osmotic pressure difference across the semi-permeable membrane. The flow penetrating from the low concentration side transports away solutes adjacent of the membrane, so that the concentration is reduced significantly only at the vicinity of the membrane. It is expected that the relatively low solute concentration develops into a thin boundary layer in the vicinity of the membrane in the case of absence of external stirring process, which is termed as un-stirred layer (USL). To investigate concentration distribution in USL, we carried out non-equilibrium molecular dynamics simulations. The flows driven by th osmotic pressure are idealized as 2 dimensional hard disk model, which is composed of solvent and solute molecules. The membrane is modeled as a medium composed of stationary parallel rods distributed by a spatial interval, which is less than the diameter of the solute molecules. The following results were obtained from the numerical simulation. First, the thickness of USL, which was estimated from the obtained concentration distribution, is on the order of a length determined by mean free path. Second, USL was semicircle the center of which is on the end of pore of membrane.
Influence of boundary slip effect on thermal environment in thermo-chemical non-equilibrium flow
NASA Astrophysics Data System (ADS)
Miao, Wenbo; Zhang, Liang; Li, Junhong; Cheng, Xiaoli
2014-12-01
A kind of new hypersonic vehicle makes long-time flight in transitional flow regime where boundary slip effect caused by low gas density will have an important influence on the thermal environment around the vehicles. Numerical studies on the boundary slip effect as hypersonic vehicles fly in high Mach number has been carried out. The method for solving non-equilibrium flows considering slip boundary, surface catalysis and chemical reactions has been built up, and been validated by comparing the thermal environment results with STS-2 flight test data. The mechanism and rules of impact on surface heat flux by different boundary slip level (Knudsen number from 0.01 to 0.05) has been investigated in typical hypersonic flow conditions. The results show that the influence mechanisms of boundary slip effect are different on component diffusion heat flux and convective heat flux; slip boundary increases the near wall temperature which diminish the convective heat; whereas enhances the near wall gas diffusion heat because of the internal energy's growing. Component diffusion heat flux takes a smaller portion of the total heat flux, so the slip boundary reduces the total wall heat flux. As Knudsen number goes up, the degree of rarefaction increases, the influences of slip boundary on convective and component diffusion heat flux are both enhanced, total heat flux grows by a small margin, and boundary slip effect is more distinct.
Relaxation of non-equilibrium entanglement networks in thin polymer films.
McGraw, Joshua D; Fowler, Paul D; Ferrari, Melissa L; Dalnoki-Veress, Kari
2013-01-01
It is known that polymer films, prepared by spin coating, inherit non-equilibrium configurations which can affect macroscopic film properties. Here we present the results of crazing experiments that support this claim; our measurements indicate that the as-cast chain configurations are strongly stretched as compared to equilibrium Gaussian configurations. The results of our experiments also demonstrate that the entanglement network equilibrates on a time scale comparable to one reptation time. Having established that films can be prepared with an equilibrium entanglement network, we proceed by confining polymers to films in which the thickness is comparable to the molecular size. By stacking two such films, a bilayer is created with a buried entropic interface. Such an interface has no enthalpic cost, only an entropic penalty associated with the restricted configurations of molecules that cannot cross the mid-plane of the bilayer. In the melt, the entropic interface heals as chains from the two layers mix and entangle with one another; crazing measurements allow us to probe the dynamics of two films becoming one. Healing of the entropic interface is found to take less than one bulk reptation time.
A process-based model for non-equilibrium clumped isotope effects in carbonates
NASA Astrophysics Data System (ADS)
Watkins, J. M.; Hunt, J. D.
2015-12-01
The equilibrium clumped isotope composition of carbonate minerals is independent of the composition of the aqueous solution. However, many carbonate minerals grow at rates that place them in a non-equilibrium regime with respect to carbon and oxygen isotopes with unknown consequences for clumped isotopes. We develop a process-based model that allows one to calculate the oxygen, carbon, and clumped isotope composition of calcite as a function of temperature, crystal growth rate, and solution pH. In the model, carbon and oxygen isotope fractionation occurs through the mass-dependent attachment/detachment kinetics of the isotopologues of HCO-3 and CO2-3 to and from the calcite surface, which in turn, influence the clumped isotope composition of calcite. At experimental and biogenic growth rates, the mineral is expected to inherit a clumped isotopic composition that is similar to that of the DIC pool, which helps to explain (1) why different organisms share the same clumped isotope versus temperature calibration curves, (2) why many inorganic calibration curves are slightly different from one another, and (3) why foraminifera, coccoliths, and deep sea corals can have near-equilibrium clumped isotope compositions but far-from-equilibrium carbon and oxygen isotope compositions. Some aspects of the model can be generalized to other mineral systems and should serve as a useful reference in future efforts to quantify kinetic clumped isotope effects.
Fundamental limits of MWIR HgCdTe barrier detectors operating under non-equilibrium mode
NASA Astrophysics Data System (ADS)
Kopytko, M.; Jóźwikowski, K.; Rogalski, A.
2014-10-01
The paper presents numerical considerations of temperature-dependent performance of different mid-wave infrared HgCdTe detectors (with p- and n-type active layer) for non-equilibrium operation. Current-voltage characteristics of double heterostructure PpN photodiode, pBppN barrier photodiode, nBnn and nBnnN barrier detectors are compared to find an optimal architecture for high-operating temperature conditions. Using our model, the calculated characteristics of the devices are fitted to the experimental results for HgCdTe photodiode grown on GaAs substrate by metal organic chemical vapour deposition. The performance of photodiodes with p-type absorber are limited by the generation current associated with the Shockley-Read-Hall process, while nBnn type devices (with the n-type absorber) indicate a diffusion limited dark currents associated with Auger processes. At high values of the reverse bias (over 1 V), the trap states located at dislocations lead to strong band-to-band and trap-assisted tunnelling due to high electric field within the depletion layer.
Non-equilibrium Statistical Mechanics and the Sea Ice Thickness Distribution
NASA Astrophysics Data System (ADS)
Wettlaufer, John; Toppaladoddi, Srikanth
We use concepts from non-equilibrium statistical physics to transform the original evolution equation for the sea ice thickness distribution g (h) due to Thorndike et al., (1975) into a Fokker-Planck like conservation law. The steady solution is g (h) = calN (q) hqe - h / H , where q and H are expressible in terms of moments over the transition probabilities between thickness categories. The solution exhibits the functional form used in observational fits and shows that for h << 1 , g (h) is controlled by both thermodynamics and mechanics, whereas for h >> 1 only mechanics controls g (h) . Finally, we derive the underlying Langevin equation governing the dynamics of the ice thickness h, from which we predict the observed g (h) . This allows us to demonstrate that the ice thickness field is ergodic. The genericity of our approach provides a framework for studying the geophysical scale structure of the ice pack using methods of broad relevance in statistical mechanics. Swedish Research Council Grant No. 638-2013-9243, NASA Grant NNH13ZDA001N-CRYO and the National Science Foundation and the Office of Naval Research under OCE-1332750 for support.
NASA Astrophysics Data System (ADS)
Hashizume, Hiroshi; Ohta, Takayuki; Mori, Takumi; Iseki, Sachiko; Hori, Masaru; Ito, Masafumi
2013-05-01
To investigate the inactivation process of Penicillium digitatum spores treated with a non-equilibrium atmospheric pressure plasma, the spores were observed using a fluorescent microscope and compared with those treated with ultraviolet (UV) light or moist heat. The treated spores were stained with two fluorescent dyes, 1,1'-dioctadecyl-3,3,Y,3'-tetramethylindocarbocyanine perchlorate (DiI) and diphenyl-1-pyrenylphosphine (DPPP). The intracellular organelles as well as cell membranes in the spores treated with the plasma were stained with DiI without a major morphological change of the membranes, while the organelles were never stained in the spores treated with UV light or moist heat. Moreover, DPPP staining revealed that organelles were oxidized by plasma treatment unlike UV light or moist heat treatments. These results suggest that only plasma treatment induces a minor structural change or functional inhibition of cell membranes, which leads to the oxidation of the intracellular organelles without a major deformation of the membranes through the penetration of reactive oxygen species generated by the plasma into the cell.
NASA Technical Reports Server (NTRS)
Liu, W. T.; Mirzabekov, A. D.; Stahl, D. A.
2001-01-01
The utility of a high-density oligonucleotide microarray (microchip) for identifying strains of five closely related bacilli (Bacillus anthracis, Bacillus cereus, Bacillus mycoides, Bacillus medusa and Bacillus subtilis) was demonstrated using an approach that compares the non-equilibrium dissociation rates ('melting curves') of all probe-target duplexes simultaneously. For this study, a hierarchical set of 30 oligonucleotide probes targeting the 16S ribosomal RNA of these bacilli at multiple levels of specificity (approximate taxonomic ranks of domain, kingdom, order, genus and species) was designed and immobilized in a high-density matrix of gel pads on a glass slide. Reproducible melting curves for probes with different levels of specificity were obtained using an optimized salt concentration. Clear discrimination between perfect match (PM) and mismatch (MM) duplexes was achieved. By normalizing the signals to an internal standard (a universal probe), a more than twofold discrimination (> 2.4x) was achieved between PM and 1-MM duplexes at the dissociation temperature at which 50% of the probe-target duplexes remained intact. This provided excellent differentiation among representatives of different Bacillus species, both individually and in mixtures of two or three. The overall pattern of hybridization derived from this hierarchical probe set also provided a clear 'chip fingerprint' for each of these closely related Bacillus species.
Visualizing non-equilibrium lithiation of spinel oxide via in situ transmission electron microscopy.
He, Kai; Zhang, Sen; Li, Jing; Yu, Xiqian; Meng, Qingping; Zhu, Yizhou; Hu, Enyuan; Sun, Ke; Yun, Hongseok; Yang, Xiao-Qing; Zhu, Yimei; Gan, Hong; Mo, Yifei; Stach, Eric A; Murray, Christopher B; Su, Dong
2016-01-01
Spinel transition metal oxides are important electrode materials for lithium-ion batteries, whose lithiation undergoes a two-step reaction, whereby intercalation and conversion occur in a sequential manner. These two reactions are known to have distinct reaction dynamics, but it is unclear how their kinetics affects the overall electrochemical response. Here we explore the lithiation of nanosized magnetite by employing a strain-sensitive, bright-field scanning transmission electron microscopy approach. This method allows direct, real-time, high-resolution visualization of how lithiation proceeds along specific reaction pathways. We find that the initial intercalation process follows a two-phase reaction sequence, whereas further lithiation leads to the coexistence of three distinct phases within single nanoparticles, which has not been previously reported to the best of our knowledge. We use phase-field theory to model and describe these non-equilibrium reaction pathways, and to directly correlate the observed phase evolution with the battery's discharge performance. PMID:27157119
NASA Astrophysics Data System (ADS)
Watson, Scott M. D.; Houlton, Andrew; Horrocks, Benjamin R.
2012-12-01
The thermodynamics of the templating of materials on one-dimensional templates, such as DNA, is modeled by considering two terms: the surface tension of the material (γ) and a line energy (σ = 2πrTγT) that represents the adhesion of the material to the template (radius rT). We show that as long as the reaction stoichiometry does not exceed a certain limit (\\sqrt{\\frac{3 v}{2 \\pi }}\\lt {r}_{T}\\frac{\\vert {\\gamma }_{T}\\vert }{\\gamma }; v = volume of material per unit length of template) then a sample of smooth, uniform wires is the equilibrium state. If the amount of material exceeds this limit, then the material will comprise a single macroscopic particle at equilibrium. The behavior of the system is similar to a morphological wetting transition and the model can rationalize the available experimental data on the reaction conditions required to form smooth DNA-templated nanowires. Using the framework of linear non-equilibrium thermodynamics, we also show that the model can describe qualitatively the observed evolution of these nanostructures from beads-on-a-string morphologies to smooth nanowires and construct a stochastic differential equation for the process. Numerical simulations and scaling arguments suggest that the same scaling behavior as the Edwards-Wilkinson equation is observed.
Collective non-equilibrium spin exchange in cold alkaline-earth atomic clocks
NASA Astrophysics Data System (ADS)
Acevedo, Oscar Leonardo; Rey, Ana Maria
2016-05-01
Alkaline-earth atomic (AEA) clocks have recently been shown to be reliable simulators of two-orbital SU(N) quantum magnetism. In this work, we study the non-equilibrium spin exchange dynamics during the clock interrogation of AEAs confined in a deep one-dimensional optical lattice and prepared in two nuclear levels. The two clock states act as an orbital degree of freedom. Every site in the lattice can be thought as populated by a frozen set of vibrational modes collectively interacting via predominantly p-wave collisions. Due to the exchange coupling, orbital state transfer between atoms with different nuclear states is expected to happen. At the mean field level, we observe that in addition to the expected suppression of population transfer in the presence of a large magnetic field, that makes the single particle levels off-resonance, there is also an interaction induced suppression for initial orbital population imbalance. This suppression resembles the macroscopic self-trapping mechanism seen in bosonic systems. However, by performing exact numerical solutions and also by using the so-called Truncated Wigner Approximation, we show that quantum correlations can significantly modify the mean field suppression. Our predictions should be testable in optical clock experiments. Project supported by NSF-PHY-1521080, JILA-NSF-PFC-1125844, ARO, AFOSR, and MURI-AFOSR.
Application Of Highly Non-Equilibrium Plasma For Modification Of Biomedical Samples
NASA Astrophysics Data System (ADS)
Mozetic, M.
2010-07-01
Non-equilibrium processing of organic materials enables modification of surface properties without changing bulk characteristics of materials. Heavily nonequilibrium state of gas is obtained in a variety of discharges, but electrode-less high frequency discharges are particularly useful. Such discharges often provide plasma with a low ionization fraction (often below 10^-5), but the dissociation fraction is often close to 100%. Neutral atoms readily react with organic materials even at room temperature. Depending on the type of organic material, both surface morphology and functionality are modified. The technique is particularly suitable for improvement of biocompatibility as well as for controlled degradation of biological cells. Several examples on the functionalization of polymer materials will be presented. Furthermore, extremely high etching selectivity of neutral oxygen atoms allows for modification of the surface roughness which, in combination with extremely high density of polar surface functional groups leads to super-hydrophilic character of some polymers. An interesting application of such technology is for modification of the surface properties of vascular grafts. Plasma treated artificial blood vessels exhibit excellent anti-thrombogenic properties as well as good ability for growing of endothelial cells. The same technique is applied for selective removal of some organic materials from biological cells. Proper treatment allows for revealing the internal structure of biological cells. Examples of treatment of different bacteria are presented.
Non-equilibrium model of two-phase porous media flow with phase change
NASA Astrophysics Data System (ADS)
Cueto-Felgueroso, L.; Fu, X.; Juanes, R.
2014-12-01
The efficient simulation of multi-phase multi-component flow through geologic porous media is challenging and computationally intensive, yet quantitative modeling of these processes is essential in engineering and the geosciences. Multiphase flow with phase change and complex phase behavior arises in numerous applications, including enhanced oil recovery, steam injection in groundwater remediation, geologic CO2 storage and enhanced geothermal energy systems. A challenge of multiphase compositional simulation is that the number of existing phases varies with position and time, and thus the number of state variables in the saturation-based conservation laws is a function of space and time. The tasks of phase-state identification and determination of the composition of the different phases are performed assuming local thermodynamic equilibrium. Here we investigate a thermodynamically consistent formulation for non-isothermal two-phase flow, in systems where the hypothesis of instantaneous local equilibrium does not hold. Non-equilibrium effects are important in coarse-scale simulations where the assumption of complete mixing in each gridblock is not realistic. We apply our model to steam injection in water-saturated porous media.
Non-equilibrium relaxation in a two-dimensional stochastic lattice Lotka-Volterra model
NASA Astrophysics Data System (ADS)
Chen, Sheng; Täuber, Uwe C.
We employ Monte Carlo simulations to study a stochastic Lotka-Volterra model on a two-dimensional square lattice with periodic boundary conditions. There are stable states when the predators and prey coexist. If the local prey carrying capacity is finite, there emerges an extinction threshold for the predator population at a critical value of the predation rate. We investigate the non-equilibrium relaxation of the predator density in the vicinity of this critical point. The expected power law dependence between the relaxation time and predation rate is observed (critical slowing down). The numerically determined associated critical exponents are in accord with the directed percolation universality class. Following a sudden predation rate change to its critical value, one observes critical aging for the predator density autocorrelation function with a universal scaling exponent. This aging scaling signature of the absorbing state phase transition emerges at significantly earlier times than stationary critical power laws, and could thus serve as an advanced indicator of the population's proximity to its extinction threshold. This research is supported by the U. S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Science and Engineering under Award DE-FG02-09ER46613.
Non-equilibrium relaxation in a stochastic lattice Lotka-Volterra model.
Chen, Sheng; Täuber, Uwe C
2016-04-19
We employ Monte Carlo simulations to study a stochastic Lotka-Volterra model on a two-dimensional square lattice with periodic boundary conditions. If the (local) prey carrying capacity is finite, there exists an extinction threshold for the predator population that separates a stable active two-species coexistence phase from an inactive state wherein only prey survive. Holding all other rates fixed, we investigate the non-equilibrium relaxation of the predator density in the vicinity of the critical predation rate. As expected, we observe critical slowing-down, i.e., a power law dependence of the relaxation time on the predation rate, and algebraic decay of the predator density at the extinction critical point. The numerically determined critical exponents are in accord with the established values of the directed percolation universality class. Following a sudden predation rate change to its critical value, one finds critical aging for the predator density autocorrelation function that is also governed by universal scaling exponents. This aging scaling signature of the active-to-absorbing state phase transition emerges at significantly earlier times than the stationary critical power laws, and could thus serve as an advanced indicator of the (predator) population's proximity to its extinction threshold.
Non-equilibrium relaxation in a stochastic lattice Lotka-Volterra model
NASA Astrophysics Data System (ADS)
Chen, Sheng; Täuber, Uwe C.
2016-04-01
We employ Monte Carlo simulations to study a stochastic Lotka-Volterra model on a two-dimensional square lattice with periodic boundary conditions. If the (local) prey carrying capacity is finite, there exists an extinction threshold for the predator population that separates a stable active two-species coexistence phase from an inactive state wherein only prey survive. Holding all other rates fixed, we investigate the non-equilibrium relaxation of the predator density in the vicinity of the critical predation rate. As expected, we observe critical slowing-down, i.e., a power law dependence of the relaxation time on the predation rate, and algebraic decay of the predator density at the extinction critical point. The numerically determined critical exponents are in accord with the established values of the directed percolation universality class. Following a sudden predation rate change to its critical value, one finds critical aging for the predator density autocorrelation function that is also governed by universal scaling exponents. This aging scaling signature of the active-to-absorbing state phase transition emerges at significantly earlier times than the stationary critical power laws, and could thus serve as an advanced indicator of the (predator) population’s proximity to its extinction threshold.
Experimental realization of atomtronic circuit elements in non-equilibrium ultracold atomic systems
NASA Astrophysics Data System (ADS)
Caliga, Seth C.
Research in the field of atomtronics aims to develop a new paradigm for the use of ultracold atomic systems in a manner that mimics the functionality of electronic circuits and devices. Given the ubiquity of the electronic transistor and its application to a vast array of signal processing tasks, the development of its atomtronic counterpart is of significant interest. This dissertation presents the experimental studies of two atomtronic circuit elements: a battery and transistor. Experiments are conducted in an atom-chip-based apparatus utilizing hybrid magnetic and optical trapping techniques that enable one to ``pattern" atomtronic circuit elements. An atomtronic battery is realized in a double-well trapping potential in which a finite-temperature Bose-Einstein condensate is prepared in a non-equilibrium state to generate thermodynamic gradients that drive atom current flow. Powered by the atomtronic battery, a triple-well atomtronic transistor is demonstrated, and quasi-steady-state behavior of the device is characterized. Results are found to be in agreement with a semiclassical model of the transistor that is also used to study the active properties of the device, including current gain. Based on these results, future directions regarding signal processing operations are proposed.
An improved dynamic non-equilibrium wall-model for large eddy simulation
NASA Astrophysics Data System (ADS)
Park, George Ilhwan; Moin, Parviz
2013-11-01
A non-equilibrium wall-model based on unsteady 3D Reynolds-averaged Navier-Stokes (RANS) equations has been implemented in an unstructured mesh environment. The method is similar to that of the wall-model described by Wang and Moin [Phys. Fluids 14, 2043-2051, (2002)], but is supplemented by a new dynamic eddy viscosity/conductivity model that corrects the effect of the resolved Reynolds stress (resolved turbulent heat flux) on the skin friction (wall heat flux). This correction is crucial for accurate prediction of the skin friction and wall heat flux. Unlike earlier models, this eddy viscosity/conductivity model does not have a stress-matching procedure or a tunable free parameter, and it shows consistent performance over a wide range of Reynolds numbers. The wall-model is validated against canonical (attached) transitional and fully turbulent flows at moderate to very high Reynolds number: a turbulent channel flow at Reτ = 2000, an H-type transitional boundary layer up to Reθ = 3300, and a high Reynolds number boundary layer at Reθ = 31000. An application to the flow over NACA4412 airfoil is ongoing and hopefully will be presented. This work was supported by the Winston and Fu-Mei Stanford Graduate Fellowship, NASA Aeronautics Scholarship Program, and NASA under the Subsonic Fixed-Wing Program and the Boeing Company.
NASA Astrophysics Data System (ADS)
Chu, Henry; Zia, Roseanna
In our recently developed non-equilibrium Stokes-Einstein relation, we showed that, in the absence of hydrodynamic interactions, the stress in a suspension is given by a balance between fluctuation and dissipation. Here, we generalize our theory for systems of hydrodynamically interacting colloids, via active microrheology, where motion of a Brownian probe through the medium reveals rheological properties. The strength of probe forcing compared to the entropic restoring force defines a Peclet number, Pe. In the absence of hydrodynamics, the first normal stress difference and the osmotic pressure scale as Pe4 and Pe2 respectively when probe forcing is weak, and uniformly as Pe for strong probe forcing. As hydrodynamics become important, interparticle forces give way to lubrication interactions. Hydrodynamic coupling leads to a new low-Pe scaling of the first normal stress difference and the osmotic pressure as Pe2, and high-Pe scaling as Peδ, where 0.799 <= δ <= 1 as hydrodynamics vary from strong to weak. For the entire range of the strength of hydrodynamic interactions and probe forcing, the new phenomenological theory is shown to agree with standard micromechanical definitions of the stress. We further draw a connection between the stress and the energy storage in a suspension, and the entropic nature of such storage is identified.
Non-equilibrium relaxation in a stochastic lattice Lotka–Volterra model
NASA Astrophysics Data System (ADS)
Chen, Sheng; Täuber, Uwe C.
2016-04-01
We employ Monte Carlo simulations to study a stochastic Lotka–Volterra model on a two-dimensional square lattice with periodic boundary conditions. If the (local) prey carrying capacity is finite, there exists an extinction threshold for the predator population that separates a stable active two-species coexistence phase from an inactive state wherein only prey survive. Holding all other rates fixed, we investigate the non-equilibrium relaxation of the predator density in the vicinity of the critical predation rate. As expected, we observe critical slowing-down, i.e., a power law dependence of the relaxation time on the predation rate, and algebraic decay of the predator density at the extinction critical point. The numerically determined critical exponents are in accord with the established values of the directed percolation universality class. Following a sudden predation rate change to its critical value, one finds critical aging for the predator density autocorrelation function that is also governed by universal scaling exponents. This aging scaling signature of the active-to-absorbing state phase transition emerges at significantly earlier times than the stationary critical power laws, and could thus serve as an advanced indicator of the (predator) population’s proximity to its extinction threshold.
The lagRST Model: A Turbulence Model for Non-Equilibrium Flows
NASA Technical Reports Server (NTRS)
Lillard, Randolph P.; Oliver, A. Brandon; Olsen, Michael E.; Blaisdell, Gregory A.; Lyrintzis, Anastasios S.
2011-01-01
This study presents a new class of turbulence model designed for wall bounded, high Reynolds number flows with separation. The model addresses deficiencies seen in the modeling of nonequilibrium turbulent flows. These flows generally have variable adverse pressure gradients which cause the turbulent quantities to react at a finite rate to changes in the mean flow quantities. This "lag" in the response of the turbulent quantities can t be modeled by most standard turbulence models, which are designed to model equilibrium turbulent boundary layers. The model presented uses a standard 2-equation model as the baseline for turbulent equilibrium calculations, but adds transport equations to account directly for non-equilibrium effects in the Reynolds Stress Tensor (RST) that are seen in large pressure gradients involving shock waves and separation. Comparisons are made to several standard turbulence modeling validation cases, including an incompressible boundary layer (both neutral and adverse pressure gradients), an incompressible mixing layer and a transonic bump flow. In addition, a hypersonic Shock Wave Turbulent Boundary Layer Interaction with separation is assessed along with a transonic capsule flow. Results show a substantial improvement over the baseline models for transonic separated flows. The results are mixed for the SWTBLI flows assessed. Separation predictions are not as good as the baseline models, but the over prediction of the peak heat flux downstream of the reattachment shock that plagues many models is reduced.
A steady-state non-equilibrium molecular dynamics approach for the study of evaporation processes.
Zhang, Jianguo; Müller-Plathe, Florian; Yahia-Ouahmed, Méziane; Leroy, Frédéric
2013-10-01
Two non-equilibrium methods (called bubble method and splitting method, respectively) have been developed and tested to study the steady state evaporation of a droplet surrounded by its vapor, where the evaporation continuously occurs at the vapor-liquid interface while the droplet size remains constant. In the bubble method, gas molecules are continuously reinserted into a free volume (represented by a bubble) located at the centre of mass of the droplet to keep the droplet size constant. In the splitting method, a molecule close to the centre of mass of the droplet is split into two: In this way, the droplet size is also maintained during the evaporation. By additional local thermostats confined to the area of insertion, the effect of frequent insertions on properties such as density and temperature can be limited to the immediate insertion area. Perturbations are not observed in other parts of the droplet. In the end, both the bubble method and the splitting method achieve steady-state droplet evaporation. Although these methods have been developed using an isolated droplet, we anticipate that they will find a wide range of applications in the study of the evaporation of isolated films and droplets or thin films on heated substrates or under confinement. They can in principle also be used to study the steady-state of other physical processes, such as the diffusion or permeation of gas molecules or ions in a pressure gradient or a concentration gradient. PMID:24116576
Non-equilibrium steady-state distributions of colloids in a tilted periodic potential
NASA Astrophysics Data System (ADS)
Ma, Xiaoguang; Lai, Pik-Yin; Ackerson, Bruce; Tong, Penger
A two-layer colloidal system is constructed to study the effects of the external force F on the non-equilibrium steady-state (NESS) dynamics of the diffusing particles over a tilted periodic potential, in which detailed balance is broken due to the presence of a steady particle flux. The periodic potential is provided by the bottom layer colloidal spheres forming a fixed crystalline pattern on a glass substrate. The corrugated surface of the bottom colloidal crystal provides a gravitational potential field for the top layer diffusing particles. By tilting the sample with respect to gravity, a tangential component F is applied to the diffusing particles. The measured NESS probability density function Pss (x , y) of the particles is found to deviate from the equilibrium distribution depending on the driving or distance from equilibrium. The experimental results are compared with the exact solution of the 1D Smoluchowski equation and the numerical results of the 2D Smoluchowski equation. Moreover, from the obtained exact 1D solution, we develop an analytical method to accurately extract the 1D potential U0 (x) from the measured Pss (x) . Work supported in part by the Research Grants Council of Hong Kong SAR.
A PDE Formulation of Non-Equilibrium Statistical Mechanics for Ionic Permeation
NASA Astrophysics Data System (ADS)
Schuss, Zeev; Nadler, Boaz; Singer, Amit; Eisenberg, Robert S.
2003-05-01
When there is a steady net flux in a system of interacting particles, the microscopic structure of the system can no longer be determined from the Boltzmann equilibrium distribution (partition function). Nonetheless, the microscopic structure of a finite system of diffusing interacting particles can be described by Poisson-Nernst-Planck-type partial differential equations. These equations, defined in a finite domain, are the non-equilibrium generalization of the BBGKY hierarchy of equilibrium statistical mechanics. Indeed, when no-flux conditions are imposed on the domain boundaries, equilibrium results are recovered. When non-homogeneous boundary conditions are given for these equations, the solutions describe densities and electrostatic potentials of particle systems not in equilibrium. The construction of a pair correlation function under these conditions will be a new result in statistical physics. As in the equilibrium case, a closure relation between a higher and a lower order correlation function has to be assumed. However, since we are considering a finite system, boundary conditions for the higher order correlation functions must also be derived. In applications to the permeation of ions through protein channels of biological membranes the computation of the pair correlation function will lead to a prediction of current through an open channel, given the spatial structure and fixed charge distribution. The pair correlation function contains finite size effects that lead to blocking in a narrow channel and possibly to selectivity.
Visualizing non-equilibrium lithiation of spinel oxide via in situ transmission electron microscopy
He, Kai; Zhang, Sen; Li, Jing; Yu, Xiqian; Meng, Qingping; Zhu, Yizhou; Hu, Enyuan; Sun, Ke; Yun, Hongseok; Yang, Xiao-Qing; Zhu, Yimei; Gan, Hong; Mo, Yifei; Stach, Eric A.; Murray, Christopher B.; Su, Dong
2016-01-01
Spinel transition metal oxides are important electrode materials for lithium-ion batteries, whose lithiation undergoes a two-step reaction, whereby intercalation and conversion occur in a sequential manner. These two reactions are known to have distinct reaction dynamics, but it is unclear how their kinetics affects the overall electrochemical response. Here we explore the lithiation of nanosized magnetite by employing a strain-sensitive, bright-field scanning transmission electron microscopy approach. This method allows direct, real-time, high-resolution visualization of how lithiation proceeds along specific reaction pathways. We find that the initial intercalation process follows a two-phase reaction sequence, whereas further lithiation leads to the coexistence of three distinct phases within single nanoparticles, which has not been previously reported to the best of our knowledge. We use phase-field theory to model and describe these non-equilibrium reaction pathways, and to directly correlate the observed phase evolution with the battery's discharge performance. PMID:27157119
Application of non-equilibrium plasmas in treatment of wool fibers and seeds
NASA Astrophysics Data System (ADS)
Petrović, Zoran
2003-10-01
While large effort is under way to achieve stable, large area, non-equilibrium plasma reactors operating at atmospheric pressure we should still consider application of low pressure reactors, which provide well defined, easily controlled reactive plasmas. Therefore, the application of low pressure rf plasmas for the treatment of wool and seed was investigated. The studies were aimed at establishing optimal procedure to achieve better wettability, dyeability and printability of wool. Plasma treatment led to a modification of wool fiber topography and formation of new polar functional groups inducing the increase of wool hydrophylicity. Plasma activation of fiber surface was also used to achieve better binding of biopolymer chitosan to wool in order to increase the content of favorable functional groups and thus improving sorption properties of recycled wool fibers for heavy metal ions and acid dyes. In another study, the increase of germination percentage of seeds induced by plasmas was investigated. We have selected dry (unimbibed) Empress tree seeds (Paulownia tomentosa Steud.). Empress tree seed has been studied extensively and its mechanism of germination is well documented. Germination of these seeds is triggered by light in a limited range of wavelengths. Interaction between activated plasma particles and seed, inside the plasma reactor, leads to changes in its surface topography, modifies the surface layer and increases the active surface area. Consequently, some bioactive nitrogeneous compounds could be bound to the activated surface layer causing the increment of germination percentage.
Exterior integrability: Yang-Baxter form of non-equilibrium steady-state density operator
NASA Astrophysics Data System (ADS)
Prosen, Tomaž; Ilievski, Enej; Popkov, Vladislav
2013-07-01
A new type of quantum transfer matrix, arising as a Cholesky factor for the steady-state density matrix of a dissipative Markovian process associated with the boundary-driven Lindblad equation for the isotropic spin-1/2 Heisenberg (XXX) chain, is presented. The transfer matrix forms a commuting family of non-Hermitian operators depending on the spectral parameter, which is essentially the strength of dissipative coupling at the boundaries. The intertwining of the corresponding Lax and monodromy matrices is performed by an infinitely dimensional Yang-Baxter R-matrix, which we construct explicitly and is essentially different from the standard 4 × 4 XXX R-matrix. We also discuss a possibility to construct Bethe ansatz for the spectrum and eigenstates of the non-equilibrium steady-state density operator. Furthermore, we indicate the existence of a deformed R-matrix in the infinite dimensional auxiliary space for the anisotropic XXZ spin-1/2 chain, which in general provides a sequence of new, possibly quasi-local, conserved quantities of the bulk XXZ dynamics.
Non-equilibrium dynamics around integrability in a one-dimensional two-component Bose gas
NASA Astrophysics Data System (ADS)
van Druten, Nicolaas; Wicke, Philipp; Whitlock, Shannon
2011-05-01
We investigate a one-dimensional two-component Bose gas near the point of state-independent interactions. At this specific point the system is integrable, in the sense that exact (thermodynamic) Bethe Ansatz solutions can be applied locally. In the experiments, we employ an atom chip and the magnetically trappable clock states in 87Rb. State-dependent potentials are generated by using the polarization dependence of radio-frequency dressing. We show that this allows us to continuously and dynamically tune both the local interactions and the global trapping potential. The experimentally accessible range in interactions includes the region around the integrability point. We study the spin motion that follows upon a sudden change in the system, a quantum quench. When starting from a low-temperature, quantum-degenerate gas in the weakly interacting regime, good agreement with a Gross-Pitaevskii description is found. The experiment allows exploring regimes that go beyond such a description and opens up a novel route to the study of the relation between non-equilibrium dynamics, thermalization and the making and breaking of integrability in quantum many-body physics. Supported by FOM, NWO and EU
A localized momentum constraint for non-equilibrium molecular dynamics simulations.
Smith, E R; Heyes, D M; Dini, D; Zaki, T A
2015-02-21
A method which controls momentum evolution in a sub-region within a molecular dynamics simulation is derived from Gauss's principle of least constraint. The technique for localization is founded on the equations by Irving and Kirkwood [J. Chem. Phys. 18, 817 (1950)] expressed in a weak form according to the control volume (CV) procedure derived by Smith et al. [Phys. Rev. E. 85, 056705 (2012)]. A term for the advection of molecules appears in the derived constraint and is shown to be essential in order to exactly control the time evolution of momentum in the subvolume. The numerical procedure converges the total momentum in the CV to the target value to within machine precision in an iterative manner. The localized momentum constraint can prescribe essentially arbitrary flow fields in non-equilibrium molecular dynamics simulations. The methodology also forms a rigorous mathematical framework for introducing coupling constraints at the boundary between continuum and discrete systems. This functionality is demonstrated with a boundary-driven flow test case.
Wexler, Adam D; Drusová, Sandra; Woisetschläger, Jakob; Fuchs, Elmar C
2016-06-28
In this experiment liquid water is subject to an inhomogeneous electric field (∇(2)Ea≈ 10(10) V m(2)) using a high voltage (20 kV) point-plane electrode system. Using interferometry it was found that the application of a strong electric field gradient to water generates local changes in the refractive index of the liquid, polarizes the surface and creates a downward moving electro-convective jet. A maximum temperature difference of 1 °C is measured in the immediate vicinity of the point electrode. Raman spectroscopy performed on water reveals an enhancement of the vibrational collective modes (3250 cm(-1)) as well as an increase in the local mode (3490 cm(-1)) energy. This bimodal enhancement indicates that the spectral changes are not due to temperature changes. The intense field gradient thus establishes an excited subpopulation of vibrational oscillators far from thermal equilibrium. Delocalization of the collective vibrational mode spatially expands this excited population beyond the microscale. Hindered rotational freedom due to electric field pinning of molecular dipoles retards the heat flow and generates a chemical potential gradient. These changes are responsible for the observed changes in the refractive index and temperature. It is demonstrated that polar liquids can thus support local non-equilibrium thermodynamic transient states critical to biochemical and environmental processes.
A microscopic, non-equilibrium, statistical field theory for cosmic structure formation
NASA Astrophysics Data System (ADS)
Bartelmann, Matthias; Fabis, Felix; Berg, Daniel; Kozlikin, Elena; Lilow, Robert; Viermann, Celia
2016-04-01
Building upon the recent pioneering work by Mazenko and by Das and Mazenko, we develop a microscopic, non-equilibrium, statistical field theory for initially correlated canonical ensembles of classical microscopic particles obeying Hamiltonian dynamics. Our primary target is cosmic structure formation, where initial Gaussian correlations in phase space are believed to be set by inflation. We give an exact expression for the generating functional of this theory and work out suitable approximations. We specify the initial correlations by a power spectrum and derive general expressions for the correlators of the density and the response field. We derive simple closed expressions for the lowest-order contributions to the nonlinear cosmological power spectrum, valid for arbitrary wave numbers. We further calculate the bispectrum expected in this theory within these approximations and the power spectrum of cosmic density fluctuations to first order in the gravitational interaction, using a recent improvement of the Zel’dovich approximation. We show that, with a modification motivated by the adhesion approximation, the nonlinear growth of the density power spectrum found in numerical simulations of cosmic structure evolution is reproduced well to redshift zero and for arbitrary wave numbers even within first-order perturbation theory. Our results present the first fully analytic calculation of the nonlinear power spectrum of cosmic structures.
The stationary non-equilibrium plasma of cosmic-ray electrons and positrons
NASA Astrophysics Data System (ADS)
Tomaschitz, Roman
2016-06-01
The statistical properties of the two-component plasma of cosmic-ray electrons and positrons measured by the AMS-02 experiment on the International Space Station and the HESS array of imaging atmospheric Cherenkov telescopes are analyzed. Stationary non-equilibrium distributions defining the relativistic electron-positron plasma are derived semi-empirically by performing spectral fits to the flux data and reconstructing the spectral number densities of the electronic and positronic components in phase space. These distributions are relativistic power-law densities with exponential cutoff, admitting an extensive entropy variable and converging to the Maxwell-Boltzmann or Fermi-Dirac distributions in the non-relativistic limit. Cosmic-ray electrons and positrons constitute a classical (low-density high-temperature) plasma due to the low fugacity in the quantized partition function. The positron fraction is assembled from the flux densities inferred from least-squares fits to the electron and positron spectra and is subjected to test by comparing with the AMS-02 flux ratio measured in the GeV interval. The calculated positron fraction extends to TeV energies, predicting a broad spectral peak at about 1 TeV followed by exponential decay.
Non-equilibrium dynamics of the complex Ginzburg-Landau equation
NASA Astrophysics Data System (ADS)
Liu, Weigang; Tauber, Uwe
The complex Ginzburg-Landau equation combines the quantum many-particle nonlinear Schrödinger equation with the time-dependent Ginzburg-Landau equation or model A relaxational dynamics. It arises in quite diverse contexts that include spontaneous pattern formation out of equilibrium, chemical oscillations, multi-mode lasers, thermal convection in binary fluids, cyclic population dynamics, and driven-dissipative Bose-Einstein condensates. Indeed, the complex Ginzburg-Landau equation exhibits a remarkably rich phase diagram with intriguing dynamics. We employ detailed numerical studies as well as analytical tools such as the perturbative renormalization group and the spherical model limit to study the non-equilibrium coarsening and critical aging scaling for the complex Ginzburg-Landau equation following quenches from an initial disordered configuration to either one of the ordered phases or the critical point. This research is supported by the U. S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Science and Engineering under Award DE-FG02-09ER46613.
The effect of turbulent fluctuations on the relaxation of thermal non-equilibrium
NASA Astrophysics Data System (ADS)
Khurshid, Sualeh; Donzis, Diego
2015-11-01
In many engineering and natural systems, the microscopic behavior of constituent molecules can affect the macroscopic behavior of the flow. This interaction is significant when the two phenomena have commensurate time scales. We study the effect of turbulence on the relaxation of thermal non-equilibrium (TNE), in particular vibrational energy relaxation, using direct numerical simulation (DNS). First order effects are observed in the evolution of both vibrational energy and turbulence. For example, the rate of decay of kinetic energy is accelerated and temperature fluctuations are amplified. Analytic expressions for equilibrium vibrational energy, Ev*,and characteristic relaxation time scale, τv, are compared against DNS data and used to understand features of the decay. This decay can be divided into two regimes, one dominated by TNE exchanges in time scales of the order of τv followed by a turbulence decay. Between the two regimes, some vibrationally hot flows become cold before reaching equilibrium. This reflects an aspect of the strong coupling between turbulence and TNE in both regimes. Compressiblity effects, quantified by turbulent Mach number (Mt), are also discussed.
Non-equilibrium relaxation in a stochastic lattice Lotka-Volterra model.
Chen, Sheng; Täuber, Uwe C
2016-04-01
We employ Monte Carlo simulations to study a stochastic Lotka-Volterra model on a two-dimensional square lattice with periodic boundary conditions. If the (local) prey carrying capacity is finite, there exists an extinction threshold for the predator population that separates a stable active two-species coexistence phase from an inactive state wherein only prey survive. Holding all other rates fixed, we investigate the non-equilibrium relaxation of the predator density in the vicinity of the critical predation rate. As expected, we observe critical slowing-down, i.e., a power law dependence of the relaxation time on the predation rate, and algebraic decay of the predator density at the extinction critical point. The numerically determined critical exponents are in accord with the established values of the directed percolation universality class. Following a sudden predation rate change to its critical value, one finds critical aging for the predator density autocorrelation function that is also governed by universal scaling exponents. This aging scaling signature of the active-to-absorbing state phase transition emerges at significantly earlier times than the stationary critical power laws, and could thus serve as an advanced indicator of the (predator) population's proximity to its extinction threshold. PMID:27092871
Tassis, Konstantinos; Willacy, Karen; Yorke, Harold W.; Turner, Neal J.
2012-07-20
We study the effect that non-equilibrium chemistry in dynamical models of collapsing molecular cloud cores has on measurements of the magnetic field in these cores, the degree of ionization, and the mean molecular weight of ions. We find that OH and CN, usually used in Zeeman observations of the line-of-sight magnetic field, have an abundance that decreases toward the center of the core much faster than the density increases. As a result, Zeeman observations tend to sample the outer layers of the core and consistently underestimate the core magnetic field. The degree of ionization follows a complicated dependence on the number density at central densities up to 10{sup 5} cm{sup -3} for magnetic models and 10{sup 6} cm{sup -3} in non-magnetic models. At higher central densities, the scaling approaches a power law with a slope of -0.6 and a normalization which depends on the cosmic-ray ionization rate {zeta} and the temperature T as ({zeta}T){sup 1/2}. The mean molecular weight of ions is systematically lower than the usually assumed value of 20-30, and, at high densities, approaches a value of 3 due to the asymptotic dominance of the H{sup +}{sub 3} ion. This significantly lower value implies that ambipolar diffusion operates faster.
The Ion-Specific, Non-Equilibrium Structural Behavior of DNA Hydrogels
NASA Astrophysics Data System (ADS)
Nguyen, Dan; Saleh, Omar
The highly tunable, sequence-dependent hybridization of DNA has enabled construction of DNA hydrogels with applications ranging from drug delivery to responsive materials. Though many have examined the structural characteristics of DNA hydrogels at equilibrium, relatively little is known about their non-equilibrium behavior, apart from their degradation rates when delivering molecular payloads. Here, we examine the effect of changing salt concentration on the dynamic formation, ageing, and degradation of DNA hydrogels comprised of branched DNA nanostars with palindromic overhangs. First, we observe that hydrogel phase is sensitive to the presence of a single unpaired base on the overhang, resulting in either a percolated network or a liquid-liquid phase separated state at high salt concentrations. Particular to the percolated network, we can induce the system to either contract or relax by changing the salt concentration. Decreasing monovalent NaCl induces the network to irreversibly contract whereas decreasing divalent MgCl2 induces the network to reversibly expand; this behavior runs counter to what is expected solely from electrostatic screening. We qualitatively understand these results by assuming that the monovalent salt modulates the dynamic hybridization between nanostar binding partners, whereas the divalent salt drives the dramatic/reversible induction of the `stacked-X' conformation in the DNA nanostars. Biomolecular Science and Engineering Program.
Scale Invariance and Self-Similarity of 1-Dimensional Non-equilibrium Suspended Sediment Transport
NASA Astrophysics Data System (ADS)
Carr, K. J.; Ercan, A.; Kavvas, M. L.
2014-12-01
The conditions under which the governing equation for non-equilibrium one-dimensional suspended sediment transport in unsteady flows is scale-invariant and self-similar are examined by applying the one-parameter Lie group of point scaling transformations. Self-similarity conditions imposed due to initial and boundary conditions are also examined. Furthermore, one-parameter Lie group point scaling transformations required to physically scale the transport process without scaling the sediment material properties are identified and investigated. Preserving sediment density and diameter is believed to eliminate some of the scale errors encountered in traditional scaling methods. Under these conditions, not only are sediment diameter and density unscaled, but so too are the critical and total shear, kinematic viscosity and particle Reynolds number. The similarity of suspended sediment transport is increased through more accurate representation of suspended sediment concentration and carrying capacity of flow. The proposed method meets the needs of modelers by; maintaining the benefits found from distortion such as reduced cost, space, and model run-time; removing the need to apply scaled sediment or surrogate sediment; avoiding some of the scale effects and resulting errors of traditional flow and sediment transport scaling.
Non-Equilibrium Dynamics of Nano-channel Confined DNA: A Brownian Dynamics Simulation Study
NASA Astrophysics Data System (ADS)
Bhattacharya, Aniket; Huang, Aiqun; Reisner, Walter
We carry out Brownian dynamics (BD) simulation for a semi-flexible polymer chain characterized by a contour length Na and a persistence length lp confined inside a rectangular nanochannel to study its compression and retraction dynamics while being pushed on one end at a constant velocity by a ``nano-dozer''. We study the evolution of one dimensional concentration profile c (x , t) and the chain extension R along the channel axis (x-axis) during both the contracting as well as the retracting phases as a function of the velocity of the nano-dozer, both in steady states and in transients. Furthermore, we measure the transverse fluctuations of the chain under contraction and retraction, and the amplitude of the density profile, and compare these simulation results with those obtained from an analytical model proposed by Khorshid et al. Our studies are guided by recent experimental results by Khorshid et al. (Phys. Rev. Lett, 113, 268104 (2014)) and provide further justification to use a one dimensional PDE approach to understand the non-equilibrium dynamics of confined polymers.
Gliding flight in snakes: non-equilibrium trajectory dynamics and kinematics
NASA Astrophysics Data System (ADS)
Socha, Jake; Miklasz, Kevin; Jafari, Farid; Vlachos, Pavlos
2010-11-01
For animal gliders that live in trees, a glide trajectory begins in free fall and, given sufficient space, transitions to equilibrium gliding with no net forces on the body. However, the dynamics of non-equilibrium gliding are not well understood. Of any terrestrial animal glider, snakes may exhibit the most complicated glide patterns resulting from their highly active undulatory behavior. Our aim was to determine the characteristics of snake gliding during the transition to equilibrium. We launched "flying" snakes (Chrysopelea paradisi) from a 15 m tower and recorded the mid-to-end portion of trajectories with four videocameras to reconstruct the snake's 3D body position. Additionally, we developed a simple analytical model of gliding assuming only steady-state forces of lift, drag and weight acting on the body and used it to explore effects of wing loading, lift-to-drag ratio, and initial velocity on trajectory dynamics. Despite the vertical space provided to transition to steady-state gliding, snakes did not exhibit equilibrium gliding and in fact displayed a net positive acceleration in the vertical axis.
A numerical study of high-pressure non-equilibrium streamers for combustion ignition application
NASA Astrophysics Data System (ADS)
Breden, Douglas; Raja, Laxminarayan L.; Idicheria, Cherian A.; Najt, Paul M.; Mahadevan, Shankar
2013-08-01
We present a computational simulation study of non-equilibrium streamer discharges in a coaxial electrode and a corona geometry for automotive combustion ignition applications. The streamers propagate in combustible fuel-air mixtures at high pressures representative of internal combustion engine conditions. The study was performed using a self-consistent, two-temperature plasma model with finite-rate plasma chemical kinetics. Positive high voltage pulses of order tens of kV and duration of tens of nanoseconds were applied to the powered inner cylindrical electrode which resulted in the formation and propagation of a cathode-directed streamer. The resulting spatial and temporal production of active radical species such as O, H, and singlet delta oxygen is quantified and compared for lean and stoichiometric fuel-air mixtures. For the coaxial electrode geometry, the discharge is characterized by a primary streamer that bridges the inter-electrode gap and a secondary streamer that develops in the wake of the primary streamer. Most of the radicals are produced in the secondary streamer. For the corona geometry, only the primary streamer is observed and the radicals are produced throughout the length of the primary streamer column. The stoichiometry of the mixture was observed to have a relatively small effect on both the plasma discharge structure and the resulting yield of radical species.
Management of Spent and Disused Radiation Sources - The Zambian Experience
Chabala, F.
2002-02-26
Zambia like all other countries in the world is faced with environmental problems brought about by a variety of human activities. In Zambia the major environmental issues as identified by Nation Environmental Action Plan (NEAP) of 1994 are water pollution, poor sanitation, land degradation, air pollution, poor waste management, misuse of chemicals, wildlife depletion and deforestation. Zambian has been using a lot of radioactive materials in its various industries. The country has taken several projects with help of external partners. These partners however left these projects in the hands of the Zambians without developing their capacities to manage these radioactive sources. The Government recognized the need to manage these sources and passed legislation governing the management of radioactive materials. The first act of Parliament on Radiation Protection work was passed in 1975 to legislate the use of ionizing radiation. However, because of financial constraints the Country is facing, these regulations have remained unimplemented. Fortunately the international Community has been working in partnership with the Zambian Government in the Management of Radioactive Material. Therefore this paper will present the following aspects of radioactive waste management in Zambia: review Existing Legislation in Zambia regarding management of spent/radioactive sources; capacity building in the field of management of radioactive waste; management of spent and disused radiation sources; existing disposal systems in Zambia regarding spent/orphaned sources; existing stocks of radioactive sources in the Zambian industries.
76 FR 6692 - Radiation Sources on Army Land
Federal Register 2010, 2011, 2012, 2013, 2014
2011-02-08
.... Background In the April 14, 2010, issue of the Federal Register (75 FR 19302), the Army issued a proposed..., 2007 (72 FR 55864) that became effective on November 30, 2007. The Army received no comments on its... Department of the Army 32 CFR Part 655 RIN 0702-AA58 Radiation Sources on Army Land AGENCY: Department of...
75 FR 19302 - Radiation Sources on Army Land
Federal Register 2010, 2011, 2012, 2013, 2014
2010-04-14
... final rule which establishes requirements for the expanded definition of byproduct material. 72 FR 55864... was made in a separate rulemaking for 10 CFR Part 110 (April 20, 2006; 71 FR 20336). The Department of... Department of the Army 32 CFR Part 655 RIN 0702-AA58 Radiation Sources on Army Land AGENCY: Department of...
Coherent Cherenkov radiation as an intense THz source
NASA Astrophysics Data System (ADS)
Bleko, V.; Karataev, P.; Konkov, A.; Kruchinin, K.; Naumenko, G.; Potylitsyn, A.; Vaughan, T.
2016-07-01
Diffraction and Cherenkov radiation of relativistic electrons from a dielectric target has been proposed as mechanism for production of intense terahertz (THz) radiation. The use of an extremely short high-energy electron beam of a 4th generation light source (X-ray free electron laser) appears to be very promising. A moderate power from the electron beam can be extracted and converted into THz radiation with nearly zero absorption losses. The initial experiment on THz observation will be performed at CLARA/VELA FEL test facility in the UK to demonstrate the principle to a wider community and to develop the radiator prototype. In this paper, we present our theoretical predictions (based on the approach of polarization currents), which provides the basis for interpreting the future experimental measurements. We will also present our hardware design and discuss a plan of the future experiment.
A source-attractor approach to network detection of radiation sources
Wu, Qishi; Barry, M. L..; Grieme, M.; Sen, Satyabrata; Rao, Nageswara S; Brooks, Richard R
2016-01-01
Radiation source detection using a network of detectors is an active field of research for homeland security and defense applications. We propose Source-attractor Radiation Detection (SRD) method to aggregate measurements from a network of detectors for radiation source detection. SRD method models a potential radiation source as a magnet -like attractor that pulls in pre-computed virtual points from the detector locations. A detection decision is made if a sufficient level of attraction, quantified by the increase in the clustering of the shifted virtual points, is observed. Compared with traditional methods, SRD has the following advantages: i) it does not require an accurate estimate of the source location from limited and noise-corrupted sensor readings, unlike the localizationbased methods, and ii) its virtual point shifting and clustering calculation involve simple arithmetic operations based on the number of detectors, avoiding the high computational complexity of grid-based likelihood estimation methods. We evaluate its detection performance using canonical datasets from Domestic Nuclear Detection Office s (DNDO) Intelligence Radiation Sensors Systems (IRSS) tests. SRD achieves both lower false alarm rate and false negative rate compared to three existing algorithms for network source detection.
Exploding Wire in Water as a Potential Source of Amplified EUV-radiation
Kolacek, Karel; Prukner, Vaclav; Schmidt, Jiri; Straus, Jaroslav; Frolov, Oleksandr; Hoffer, Petr
2009-01-21
Proximity wall stabilized, fast (>4x10{sup 11} A/s), high current (>40 kA) discharges are capable to create long, dense, hot, 'stable,' non-equilibrium plasma column suitable e.g. for amplification of EUV and soft X-ray radiation. Exploding wire in water resembles a metal-vapor-filled capillary with liquid, ever fresh wall (without any metallic deposit). Modeling of wire explosion (inclusive melting and boiling phase transitions, thermal diffusion, and non-constant conductivity) by the originally skinned driving current is described. Modeling results are compared with measurement of the discharge current and with side-on monitoring of H-alpha line emission. The differences are attributed to the fact that for calculation the material constants measured at atmospheric pressure were available only.
Designation and nomenclature for astronomical sources of radiation
NASA Astrophysics Data System (ADS)
Dickel, H. R.; Lortet, M.-C.; de Boer, K. S.
1987-02-01
A nomenclature designation scheme for astronomical radiation sources, adopted by the IAU in Resolutions C3 and C12 on Astronomical Designations and Radio Source Nomenclature, is discussed. The proposed scheme is of the form: DDDD Errrrrrr + or - rrrrrrr (NNNNN) sssss, in which DDD represents the detection technique, observatory or observer(s) name(s); E is the code for the standard epoch and type of coordinate; NNNNN is the source or association name; and sssss are further specifiers, as needed. The first two designations are mandatory and the last two are optional. Other methods and schemes are also considered.
[Research on ground scenery spectral radiation source with tunable spectra].
Xiang, Jin-rong; Ren, Jian-wei; Li, Bao-yong; Wan, Zhi; Liu, Ze-xun; Liu, Hong-xing; Li, Xian-sheng; Sun, Jing-xu
2015-02-01
A spectrum-tunable ground scenery spectrum radiation source, using LEDs and bromine tungsten lamp as luminescence media, was introduced. System structure and control of the spectrum radiation source was expounded in detail. In order to simulate various ground scenery spectrum distribution with different shapes, a ground scenery spectral database was established in the control system. An improved genetic algorithm was proposed, and a large number of ground scenery spectra were produced by the simulator. Spectral similarity and the average spectral matching error of several typical ground scenery spectra were further analyzed. Spectral similarity of red bands, green bands, blue bands and near-infrared spectral band also was discussed. When the radiance of the target was 50 W x (m2 x sr)(-1), the average spectral matching error was less than 10% and spectral similarity was greater than 0.9, up to 0.983. Spectral similarity of red band, green band, blue band and near-infrared band (especially green band and near-infrared band) was less than that of full-band. Compared with blue band and red band, spectral similarity of green band and near-infrared band low-amplitude maximum can rearch 50%. Ground scenery spectrum radiation source can be used as radiometric calibration source for optical remote sensor, and calibration error, which is caused by objectives and calibration sources spectral mismatch, can be effectively reduced. PMID:25970881
Xu, Liufang; Shi, Hualin; Feng, Haidong; Wang, Jin
2012-04-28
The global stability of dynamical systems and networks is still challenging to study. We developed a landscape and flux framework to explore the global stability. The potential landscape is directly linked to the steady state probability distribution of the non-equilibrium dynamical systems which can be used to study the global stability. The steady state probability flux together with the landscape gradient determines the dynamics of the system. The non-zero probability flux implies the breaking down of the detailed balance which is a quantitative signature of the systems being in non-equilibrium states. We investigated the dynamics of several systems from monostability to limit cycle and explored the microscopic origin of the probability flux. We discovered that the origin of the probability flux is due to the non-equilibrium conditions on the concentrations resulting energy input acting like non-equilibrium pump or battery to the system. Another interesting behavior we uncovered is that the probabilistic flux is closely related to the steady state deterministic chemical flux. For the monostable model of the kinetic cycle, the analytical expression of the probabilistic flux is directly related to the deterministic flux, and the later is directly generated by the chemical potential difference from the adenosine triphosphate (ATP) hydrolysis. For the limit cycle of the reversible Schnakenberg model, we also show that the probabilistic flux is correlated to the chemical driving force, as well as the deterministic effective flux. Furthermore, we study the phase coherence of the stochastic oscillation against the energy pump, and argue that larger non-equilibrium pump results faster flux and higher coherence. This leads to higher robustness of the biological oscillations. We also uncovered how fluctuations influence the coherence of the oscillations in two steps: (1) The mild fluctuations influence the coherence of the system mainly through the probability flux while
Characterization of Z-Pinch Driven Hohlraum Radiation Sources*
NASA Astrophysics Data System (ADS)
Porter, J. L.; Chandler, G. A.; Deeney, C.; Fehl, D. L.; Noack, D. D.; Olson, R. E.; Ruggles, L. E.; Seaman, J. F.; Spielman, R. B.; Torres, J. A.; Vargas, M. F.; Bartlett, R. J.; Benage, J. F., Jr.; Idzorek, G. C.
1996-11-01
We have developed a z-pinch-driven soft x-ray radiation source that is near-Planckian in spectral shape and very uniform over spatial dimensions of several millimeters. We create this radiation source by surrounding a z-pinch implosion with a high-Z radiation case (a hohlraum). This experimental arrangement is referred to as the =B3vacuum hohlraum=B2 configuration. We have measured hohlraum temperatures of greater than 75 eV which last for 10=B9s of nanoseconds using the 7-MA Saturn accelerator. We will begin z-pinch experiments this fall using the 16-MA PBFA-Z accelerator. The PBFA-Z driver will be able to produce hohlraums with radiation temperatures well in excess of 100 eV. In this presentation we will describe measurements of the time history of the x-ray power, spectrum, and spatial uniformity of hohlraums produced using the Saturn accelerator. We will also present preliminary measurements of the radiation temperature of hohlraums created using the recently commissioned PBFA-Z accelerator. *This work supported by the U.S. Department of Energy under contract DE-AC04-94AL85000.
Nuisance Source Population Modeling for Radiation Detection System Analysis
Sokkappa, P; Lange, D; Nelson, K; Wheeler, R
2009-10-05
A major challenge facing the prospective deployment of radiation detection systems for homeland security applications is the discrimination of radiological or nuclear 'threat sources' from radioactive, but benign, 'nuisance sources'. Common examples of such nuisance sources include naturally occurring radioactive material (NORM), medical patients who have received radioactive drugs for either diagnostics or treatment, and industrial sources. A sensitive detector that cannot distinguish between 'threat' and 'benign' classes will generate false positives which, if sufficiently frequent, will preclude it from being operationally deployed. In this report, we describe a first-principles physics-based modeling approach that is used to approximate the physical properties and corresponding gamma ray spectral signatures of real nuisance sources. Specific models are proposed for the three nuisance source classes - NORM, medical and industrial. The models can be validated against measured data - that is, energy spectra generated with the model can be compared to actual nuisance source data. We show by example how this is done for NORM and medical sources, using data sets obtained from spectroscopic detector deployments for cargo container screening and urban area traffic screening, respectively. In addition to capturing the range of radioactive signatures of individual nuisance sources, a nuisance source population model must generate sources with a frequency of occurrence consistent with that found in actual movement of goods and people. Measured radiation detection data can indicate these frequencies, but, at present, such data are available only for a very limited set of locations and time periods. In this report, we make more general estimates of frequencies for NORM and medical sources using a range of data sources such as shipping manifests and medical treatment statistics. We also identify potential data sources for industrial source frequencies, but leave the task of
Radiation thermometer size-of-source effect testing using aperture
Liebmann, F.; Kolat, T.
2013-09-11
Size-of-source effect is an important attribute of any radiation thermometer. The effects of this attribute may be quantified in a number of different ways to include field-of-view, distance ratio, or size-of-source effect. These parameters provide needed information for the user of a radiation thermometer, as they aid in determining whether the measured object is large enough for adequate radiation thermometry measurement. Just as important, these parameters provide needed information for calibration. This information helps to determine calibration geometry, and it is needed for calibration uncertainty determination. For determination of size-of-source effect, there are a limited number of test methods furnished by the standards available today. The test methods available may be cumbersome to perform due to the cost of the required equipment and the time needed to set-up and perform the test. Other methods have been proposed. This paper discusses one such method. This method uses a circular aperture such as that used in radiation thermometer calibration. It describes the method both theoretically and mechanically. It then discusses testing done to verify this method comparing the results to those obtained while performing steps in current standards. Finally, based on this testing, the basis for a new standard test method is presented.
Light-emitting diodes as a radiation source for plants
NASA Technical Reports Server (NTRS)
Bula, R. J.; Morrow, R. C.; Tibbitts, T. W.; Barta, D. J.; Ignatius, R. W.; Martin, T. S.
1991-01-01
Development of a more effective radiation source for use in plant-growing facilities would be of significant benefit for both research and commercial crop production applications. An array of light-emitting diodes (LEDs) that produce red radiation, supplemented with a photosynthetic photon flux (PPF) of 30 micromoles s-1 m-2 in the 400- to 500-nm spectral range from blue fluorescent lamps, was used effectively as a radiation source for growing plants. Growth of lettuce (Lactuca sativa L. Grand Rapids') plants maintained under the LED irradiation system at a total PPF of 325 micromoles s-1 m-2 for 21 days was equivalent to that reported in the literature for plants grown for the same time under cool-white fluorescent and incandescent radiation sources. Characteristics of the plants, such as leaf shape, color, and texture, were not different from those found with plants grown under cool-white fluorescent lamps. Estimations of the electrical energy conversion efficiency of a LED system for plant irradiation suggest that it may be as much as twice that published for fluorescent systems.
Light-emitting diodes as a radiation source for plants.
Bula, R J; Morrow, R C; Tibbitts, T W; Barta, D J; Ignatius, R W; Martin, T S
1991-02-01
Development of a more effective radiation source for use in plant-growing facilities would be of significant benefit for both research and commercial crop production applications. An array of light-emitting diodes (LEDs) that produce red radiation, supplemented with a photosynthetic photon flux (PPF) of 30 micromoles s-1 m-2 in the 400- to 500-nm spectral range from blue fluorescent lamps, was used effectively as a radiation source for growing plants. Growth of lettuce (Lactuca sativa L. Grand Rapids') plants maintained under the LED irradiation system at a total PPF of 325 micromoles s-1 m-2 for 21 days was equivalent to that reported in the literature for plants grown for the same time under cool-white fluorescent and incandescent radiation sources. Characteristics of the plants, such as leaf shape, color, and texture, were not different from those found with plants grown under cool-white fluorescent lamps. Estimations of the electrical energy conversion efficiency of a LED system for plant irradiation suggest that it may be as much as twice that published for fluorescent systems.
Bimodality of low-redshift circumgalactic O VI in non-equilibrium EAGLE zoom simulations
NASA Astrophysics Data System (ADS)
Oppenheimer, Benjamin D.; Crain, Robert A.; Schaye, Joop; Rahmati, Alireza; Richings, Alexander J.; Trayford, James W.; Tumlinson, Jason; Bower, Richard G.; Schaller, Matthieu; Theuns, Tom
2016-08-01
We introduce a series of 20 cosmological hydrodynamical simulations of L* (M200 = 1011.7-1012.3 M⊙) and group-sized (M200 = 1012.7-1013.3 M⊙) haloes run with the model used for the EAGLE project, which additionally includes a non-equilibrium ionization and cooling module that follows 136 ions. The simulations reproduce the observed correlation, revealed by COS-Halos at z ˜ 0.2, between {O {VI}} column density at impact parameters b < 150 kpc and the specific star formation rate (sSFR ≡ SFR/M*) of the central galaxy at z ˜ 0.2. We find that the column density of circumgalactic {O {VI}} is maximal in the haloes associated with L* galaxies, because their virial temperatures are close to the temperature at which the ionization fraction of {O {VI}} peaks (T ˜ 105.5 K). The higher virial temperature of group haloes (>106 K) promotes oxygen to higher ionization states, suppressing the {O {VI}} column density. The observed N_{O {VI}}-sSFR correlation therefore does not imply a causal link, but reflects the changing characteristic ionization state of oxygen as halo mass is increased. In spite of the mass dependence of the oxygen ionization state, the most abundant circumgalactic oxygen ion in both L* and group haloes is {O VII}; {O {VI}} accounts for only 0.1 per cent of the oxygen in group haloes and 0.9-1.3 per cent with L* haloes. Nonetheless, the metals traced by {O {VI}} absorbers represent a fossil record of the feedback history of galaxies over a Hubble time; their characteristic epoch of ejection corresponds to z > 1 and much of the ejected metal mass resides beyond the virial radius of galaxies. For both L* and group galaxies, more of the oxygen produced and released by stars in the circumgalactic medium (within twice the virial radius) than in the stars and interstellar medium of the galaxy.
Flow reactor studies of non-equilibrium plasma-assisted oxidation of n-alkanes.
Tsolas, Nicholas; Lee, Jong Guen; Yetter, Richard A
2015-08-13
The oxidation of n-alkanes (C1-C7) has been studied with and without the effects of a nanosecond, non-equilibrium plasma discharge at 1 atm pressure from 420 to 1250 K. Experiments have been performed under nearly isothermal conditions in a flow reactor, where reactive mixtures are diluted in Ar to minimize temperature changes from chemical reactions. Sample extraction performed at the exit of the reactor captures product and intermediate species and stores them in a multi-position valve for subsequent identification and quantification using gas chromatography. By fixing the flow rate in the reactor and varying the temperature, reactivity maps for the oxidation of fuels are achieved. Considering all the fuels studied, fuel consumption under the effects of the plasma is shown to have been enhanced significantly, particularly for the low-temperature regime (T<800 K). In fact, multiple transitions in the rates of fuel consumption are observed depending on fuel with the emergence of a negative-temperature-coefficient regime. For all fuels, the temperature for the transition into the high-temperature chemistry is lowered as a consequence of the plasma being able to increase the rate of fuel consumption. Using a phenomenological interpretation of the intermediate species formed, it can be shown that the active particles produced from the plasma enhance alkyl radical formation at all temperatures and enable low-temperature chain branching for fuels C3 and greater. The significance of this result demonstrates that the plasma provides an opportunity for low-temperature chain branching to occur at reduced pressures, which is typically observed at elevated pressures in thermal induced systems. PMID:26170423
Colloidal dispersions in external fields: from equilibrium to non-equilibrium
NASA Astrophysics Data System (ADS)
Lowen, Hartmut
2010-03-01
Dispersions of colloidal particles are excellent model systems of classical statistical mechanics in order to understand the principles of self-organization processes. Using an external field (e.g. electric or magnetic field) the effective interaction between the colloidal particles can be tailored and the system can be brought into non-equilibrium in a controlled way. Glass formation after an ultrafast quench in a two-dimensional superparamagnetic binary colloidal mixture [1,2] will be discussed as well as lane [3,4,5,6,7] and band [8] formation in mixtures of charged suspensions and dusty plasmas driven by an electric field. [4pt] References:[0pt] [1] L. Assoud, F. Ebert, P. Keim, R. Messina, G. Maret, H. Lowen, Phys. Rev. Letters 102, 238301 (2009). [0pt] [2] L. Assoud, F. Ebert, P. Keim, R. Messina, G. Maret, H. Lowen, J. Phys.: Condensed Matter 21, 464114 (2009). [0pt] [3] J. Dzubiella, G. P. Hoffmann, H. Lowen, Phys. Rev. E 65, 021402 (1-8) (2002). [0pt] [4] M. E. Leunissen, C. G. Christova, A. P. Hynninen, C. P. Royall, A. I. Campbell, A. Imhof, M. Dijkstra, R. van Roij, A. van Blaaderen, Nature 437, 235 (2005). [0pt] [5] M. Rex, H. Lowen, Phys. Rev. E 75, 051402 (2007). [0pt] [6] M. Rex, C. P. Royall, A. van Blaaderen, H. Lowen, Lane formation in driven colloidal mixtures: is it continuous or discontinuous?, http://arxiv.org/abs/0812.0908 [0pt] [7] K. R. Sutterlin, A. Wysocki, A. V. Ivlev, C. Rath, H. M. Thomas, M. Rubin-Zuzic, W. J. Goedheer, V. E. Fortov, A. M. Lipaev, V. I. Molotkov, O. F. Petrov, G. E. Morfill, H. Lowen, Phys. Rev. Letters 102, 085003 (2009). [0pt] [8] A. Wysocki, H. Lowen, Phys. Rev. E 79, 041408 (2009).
Giavazzi, Fabio; Savorana, Giovanni; Vailati, Alberto; Cerbino, Roberto
2016-08-21
Linearised fluctuating hydrodynamics describes effectively the concentration non-equilibrium fluctuations (NEF) arising during a diffusion process driven by a small concentration gradient. However, fluctuations in the presence of large gradients are not yet fully understood. Here we study the giant concentration NEF arising when a dense aqueous colloidal suspension is allowed to diffuse into an overlying layer of pure water. We use differential dynamic microscopy to determine both the statics and the dynamics of the fluctuations for several values of the wave-vector q. At small q, NEF are quenched by buoyancy, which prevents their full development and sets an upper timescale to their temporal relaxation. At intermediate q, the mean squared amplitude of NEF is characterised by a power law exponent -4, and fluctuations relax diffusively with diffusion coefficient D1. At large q, the amplitude of NEF vanishes and equilibrium concentration fluctuations are recovered, enabling a straightforward determination of the osmotic compressibility of the suspension during diffusion. In this q-range we also find that the relaxation of the fluctuations occurs with a diffusion coefficient D2 significantly different from D1. Both diffusion coefficients exhibit time-dependence with D1 increasing monotonically (by about 15%) and D2 showing the opposite behaviour (about 17% decrease). At equilibrium, the two coefficients coincide as expected. While the decrease of D2 is compatible with a diffusive evolution of the concentration profile, the increase of D1 is still not fully understood and may require considering nonlinearities that are neglected in current theories for highly stressed colloids.
Flow reactor studies of non-equilibrium plasma-assisted oxidation of n-alkanes.
Tsolas, Nicholas; Lee, Jong Guen; Yetter, Richard A
2015-08-13
The oxidation of n-alkanes (C1-C7) has been studied with and without the effects of a nanosecond, non-equilibrium plasma discharge at 1 atm pressure from 420 to 1250 K. Experiments have been performed under nearly isothermal conditions in a flow reactor, where reactive mixtures are diluted in Ar to minimize temperature changes from chemical reactions. Sample extraction performed at the exit of the reactor captures product and intermediate species and stores them in a multi-position valve for subsequent identification and quantification using gas chromatography. By fixing the flow rate in the reactor and varying the temperature, reactivity maps for the oxidation of fuels are achieved. Considering all the fuels studied, fuel consumption under the effects of the plasma is shown to have been enhanced significantly, particularly for the low-temperature regime (T<800 K). In fact, multiple transitions in the rates of fuel consumption are observed depending on fuel with the emergence of a negative-temperature-coefficient regime. For all fuels, the temperature for the transition into the high-temperature chemistry is lowered as a consequence of the plasma being able to increase the rate of fuel consumption. Using a phenomenological interpretation of the intermediate species formed, it can be shown that the active particles produced from the plasma enhance alkyl radical formation at all temperatures and enable low-temperature chain branching for fuels C3 and greater. The significance of this result demonstrates that the plasma provides an opportunity for low-temperature chain branching to occur at reduced pressures, which is typically observed at elevated pressures in thermal induced systems.
Dan, K; Roy, M; Datta, A
2016-02-14
The present manuscript describes the role of entropic and enthalpic forces mediated by organic non-polar (hexane) and polar (methanol) solvents on the bulk and microscopic phase transition of a well known nematic liquid crystalline material MBBA (N-(4-methoxybenzylidene)-4-butylaniline) through Differential Scanning calorimetry (DSC), UV-Visible (UV-Vis), and Fourier Transform Infrared (FTIR) spectroscopy. DSC study indicates continuous linear decreases in both nematic-isotropic (N-I) phase transition temperature and enthalpy of MBBA in presence of hexane while both these parameters show a saturation after an initial decay in methanol. These distinct transitional behaviours were explained in terms of the "depletion force" model for entropic screening in hexane and "screening-self-screening" model for methanol. Heating rate dependent DSC studies find that non-Arrhenius behaviour, characteristic of pristine MBBA and a manifestation of non-equilibrium nature [Dan et al., J. Chem. Phys. 143, 094501 (2015)], is preserved in presence of entropic screening in the hexane solution, while it changes to Arrhenius behaviour (signifying equilibrium behaviour) in presence of enthalpic screening in methanol solution. FTIR spectra show similar dependence on the solvent induced screening in the intensities of the imine (-C = N) stretch and the out-of-plane distortion vibrations of the benzene rings of MBBA with hexane and methanol as in DSC, further establishing our entropic and enthalpic screening models. UV-Vis spectra of the electronic transitions in MBBA as a function of temperature also exhibit different dependences of intensities on the solvent induced screening, and an exponential decrease is observed in presence of hexane while methanol completely changes the nature of interaction to follow a linear dependence. PMID:26874498
2-D Modeling of Nanoscale MOSFETs: Non-Equilibrium Green's Function Approach
NASA Technical Reports Server (NTRS)
Svizhenko, Alexei; Anantram, M. P.; Govindan, T. R.; Biegel, Bryan
2001-01-01
We have developed physical approximations and computer code capable of realistically simulating 2-D nanoscale transistors, using the non-equilibrium Green's function (NEGF) method. This is the most accurate full quantum model yet applied to 2-D device simulation. Open boundary conditions and oxide tunneling are treated on an equal footing. Electrons in the ellipsoids of the conduction band are treated within the anisotropic effective mass approximation. Electron-electron interaction is treated within Hartree approximation by solving NEGF and Poisson equations self-consistently. For the calculations presented here, parallelization is performed by distributing the solution of NEGF equations to various processors, energy wise. We present simulation of the "benchmark" MIT 25nm and 90nm MOSFETs and compare our results to those from the drift-diffusion simulator and the quantum-corrected results available. In the 25nm MOSFET, the channel length is less than ten times the electron wavelength, and the electron scattering time is comparable to its transit time. Our main results are: (1) Simulated drain subthreshold current characteristics are shown, where the potential profiles are calculated self-consistently by the corresponding simulation methods. The current predicted by our quantum simulation has smaller subthreshold slope of the Vg dependence which results in higher threshold voltage. (2) When gate oxide thickness is less than 2 nm, gate oxide leakage is a primary factor which determines off-current of a MOSFET (3) Using our 2-D NEGF simulator, we found several ways to drastically decrease oxide leakage current without compromising drive current. (4) Quantum mechanically calculated electron density is much smaller than the background doping density in the poly silicon gate region near oxide interface. This creates an additional effective gate voltage. Different ways to. include this effect approximately will be discussed.
Construction of Low Dissipative High Order Well-Balanced Filter Schemes for Non-Equilibrium Flows
NASA Technical Reports Server (NTRS)
Wang, Wei; Yee, H. C.; Sjogreen, Bjorn; Magin, Thierry; Shu, Chi-Wang
2009-01-01
The goal of this paper is to generalize the well-balanced approach for non-equilibrium flow studied by Wang et al. [26] to a class of low dissipative high order shock-capturing filter schemes and to explore more advantages of well-balanced schemes in reacting flows. The class of filter schemes developed by Yee et al. [30], Sjoegreen & Yee [24] and Yee & Sjoegreen [35] consist of two steps, a full time step of spatially high order non-dissipative base scheme and an adaptive nonlinear filter containing shock-capturing dissipation. A good property of the filter scheme is that the base scheme and the filter are stand alone modules in designing. Therefore, the idea of designing a well-balanced filter scheme is straightforward, i.e., choosing a well-balanced base scheme with a well-balanced filter (both with high order). A typical class of these schemes shown in this paper is the high order central difference schemes/predictor-corrector (PC) schemes with a high order well-balanced WENO filter. The new filter scheme with the well-balanced property will gather the features of both filter methods and well-balanced properties: it can preserve certain steady state solutions exactly; it is able to capture small perturbations, e.g., turbulence fluctuations; it adaptively controls numerical dissipation. Thus it shows high accuracy, efficiency and stability in shock/turbulence interactions. Numerical examples containing 1D and 2D smooth problems, 1D stationary contact discontinuity problem and 1D turbulence/shock interactions are included to verify the improved accuracy, in addition to the well-balanced behavior.
Topics in Non-Equilibrium Dynamics and the Emergence of Spacetime
NASA Astrophysics Data System (ADS)
Engelhardt, Dalit
The Anti-de Sitter / Conformal Field Theory (AdS/CFT) correspondence that arises in string theory has had implications for the study of phenomena across a range of subfields in physics, from spacetime geometry to the behavior of condensed matter systems. Two major themes that have featured prominently in these investigations have been the behavior of systems out of equilibrium, and the emergence of spacetime. In this thesis, aspects of these themes are considered and analyzed. The question of equilibration and thermalization in 2D conformal field theories is addressed and refined via a number of observations about local versus global thermalization in such systems, the validity of particular diagnostics of thermalization, the dependence of the equilibration behavior of a conformal field theory on its operator spectrum, and the holographic dual of the generalized Gibbs ensemble that is of interest in studies of equilibration in systems with a large number of conserved quantities. A formalism for analyzing the non-equilibrium dynamics of 1+1-dimensional conformal field theories is discussed, and its physical relevance is motivated with an example connecting such a system to an experimental system that exhibited unusual equilibration behavior. Qualitative agreement is demonstrated between the CFT picture and the experimental observations. The emergence of spacetime geometry from quantum entanglement, while largely a byproduct of considerations from holographic dualities, has also been proposed to have a direct, non-holographic manifestation. Here a particular realization of such a direct emergence is presented through a demonstration that, in the presence of quantum entanglement alone, certain observations of electric fields in the entangled system appear qualitatively the same as the corresponding observations in a physically-connected geometric spacetime, so that the entanglement effectively mimics particular features associated with geometric connectivity.
SDSS J141624.08+134826.7: Blue L dwarfs and Non-equilibrium Chemistry
NASA Astrophysics Data System (ADS)
Cushing, Michael C.; Saumon, D.; Marley, Mark S.
2010-11-01
We present an analysis of the recently discovered blue L dwarf SDSS J141624.08+134826.7. We extend the spectral coverage of its published spectrum to ~4 μm by obtaining a low-resolution L-band spectrum with SpeX on the NASA IRTF. The spectrum exhibits a tentative weak CH4 absorption feature at 3.3 μm but is otherwise featureless. We derive the atmospheric parameters of SDSS J141624.08+134826.7 by comparing its 0.7-4.0 μm spectrum to the atmospheric models of Marley and Saumon which include the effects of both condensate cloud formation and non-equilibrium chemistry due to vertical mixing and find the best-fitting model has T eff = 1700 K, log g = 5.5 (cm s-2), f sed = 4, and K zz = 104 cm2 s-1. The derived effective temperature is significantly cooler than previously estimated but we confirm the suggestion by Bowler et al. that the peculiar spectrum of SDSS J141624.08+134826.7 is primarily a result of thin condensate clouds. In addition, we find strong evidence of vertical mixing in the atmosphere of SDSS J141624.08+134826.7 based on the absence of the deep 3.3 μm CH4 absorption band predicted by models computed in chemical equilibrium. Finally, this result suggests that observations of blue L dwarfs are an appealing way to quantitatively estimate the vigor of mixing in the atmospheres of L dwarfs because of the dramatic impact such mixing has on the strength of the 3.3 μm CH4 band in the emergent spectra of L dwarfs with thin condensate clouds.
Non-equilibrium simulations of thermally induced electric fields in water
NASA Astrophysics Data System (ADS)
Wirnsberger, P.; Fijan, D.; Šarić, A.; Neumann, M.; Dellago, C.; Frenkel, D.
2016-06-01
Using non-equilibrium molecular dynamics simulations, it has been recently demonstrated that water molecules align in response to an imposed temperature gradient, resulting in an effective electric field. Here, we investigate how thermally induced fields depend on the underlying treatment of long-ranged interactions. For the short-ranged Wolf method and Ewald summation, we find the peak strength of the field to range between 2 × 107 and 5 × 107 V/m for a temperature gradient of 5.2 K/Å. Our value for the Wolf method is therefore an order of magnitude lower than the literature value [J. A. Armstrong and F. Bresme, J. Chem. Phys. 139, 014504 (2013); J. Armstrong et al., J. Chem. Phys. 143, 036101 (2015)]. We show that this discrepancy can be traced back to the use of an incorrect kernel in the calculation of the electrostatic field. More seriously, we find that the Wolf method fails to predict correct molecular orientations, resulting in dipole densities with opposite sign to those computed using Ewald summation. By considering two different multipole expansions, we show that, for inhomogeneous polarisations, the quadrupole contribution can be significant and even outweigh the dipole contribution to the field. Finally, we propose a more accurate way of calculating the electrostatic potential and the field. In particular, we show that averaging the microscopic field analytically to obtain the macroscopic Maxwell field reduces the error bars by up to an order of magnitude. As a consequence, the simulation times required to reach a given statistical accuracy decrease by up to two orders of magnitude.
Many-body quantum electrodynamics networks: Non-equilibrium condensed matter physics with light
NASA Astrophysics Data System (ADS)
Le Hur, Karyn; Henriet, Loïc; Petrescu, Alexandru; Plekhanov, Kirill; Roux, Guillaume; Schiró, Marco
2016-10-01
We review recent developments regarding the quantum dynamics and many-body physics with light, in superconducting circuits and Josephson analogues, by analogy with atomic physics. We start with quantum impurity models addressing dissipative and driven systems. Both theorists and experimentalists are making efforts towards the characterization of these non-equilibrium quantum systems. We show how Josephson junction systems can implement the equivalent of the Kondo effect with microwave photons. The Kondo effect can be characterized by a renormalized light frequency and a peak in the Rayleigh elastic transmission of a photon. We also address the physics of hybrid systems comprising mesoscopic quantum dot devices coupled with an electromagnetic resonator. Then, we discuss extensions to Quantum Electrodynamics (QED) Networks allowing one to engineer the Jaynes-Cummings lattice and Rabi lattice models through the presence of superconducting qubits in the cavities. This opens the door to novel many-body physics with light out of equilibrium, in relation with the Mott-superfluid transition observed with ultra-cold atoms in optical lattices. Then, we summarize recent theoretical predictions for realizing topological phases with light. Synthetic gauge fields and spin-orbit couplings have been successfully implemented in quantum materials and with ultra-cold atoms in optical lattices - using time-dependent Floquet perturbations periodic in time, for example - as well as in photonic lattice systems. Finally, we discuss the Josephson effect related to Bose-Hubbard models in ladder and two-dimensional geometries, producing phase coherence and Meissner currents. The Bose-Hubbard model is related to the Jaynes-Cummings lattice model in the large detuning limit between light and matter (the superconducting qubits). In the presence of synthetic gauge fields, we show that Meissner currents subsist in an insulating Mott phase.
Giavazzi, Fabio; Savorana, Giovanni; Vailati, Alberto; Cerbino, Roberto
2016-08-21
Linearised fluctuating hydrodynamics describes effectively the concentration non-equilibrium fluctuations (NEF) arising during a diffusion process driven by a small concentration gradient. However, fluctuations in the presence of large gradients are not yet fully understood. Here we study the giant concentration NEF arising when a dense aqueous colloidal suspension is allowed to diffuse into an overlying layer of pure water. We use differential dynamic microscopy to determine both the statics and the dynamics of the fluctuations for several values of the wave-vector q. At small q, NEF are quenched by buoyancy, which prevents their full development and sets an upper timescale to their temporal relaxation. At intermediate q, the mean squared amplitude of NEF is characterised by a power law exponent -4, and fluctuations relax diffusively with diffusion coefficient D1. At large q, the amplitude of NEF vanishes and equilibrium concentration fluctuations are recovered, enabling a straightforward determination of the osmotic compressibility of the suspension during diffusion. In this q-range we also find that the relaxation of the fluctuations occurs with a diffusion coefficient D2 significantly different from D1. Both diffusion coefficients exhibit time-dependence with D1 increasing monotonically (by about 15%) and D2 showing the opposite behaviour (about 17% decrease). At equilibrium, the two coefficients coincide as expected. While the decrease of D2 is compatible with a diffusive evolution of the concentration profile, the increase of D1 is still not fully understood and may require considering nonlinearities that are neglected in current theories for highly stressed colloids. PMID:27425869
NASA Astrophysics Data System (ADS)
Dan, K.; Roy, M.; Datta, A.
2016-02-01
The present manuscript describes the role of entropic and enthalpic forces mediated by organic non-polar (hexane) and polar (methanol) solvents on the bulk and microscopic phase transition of a well known nematic liquid crystalline material MBBA (N-(4-methoxybenzylidene)-4-butylaniline) through Differential Scanning calorimetry (DSC), UV-Visible (UV-Vis), and Fourier Transform Infrared (FTIR) spectroscopy. DSC study indicates continuous linear decreases in both nematic-isotropic (N-I) phase transition temperature and enthalpy of MBBA in presence of hexane while both these parameters show a saturation after an initial decay in methanol. These distinct transitional behaviours were explained in terms of the "depletion force" model for entropic screening in hexane and "screening-self-screening" model for methanol. Heating rate dependent DSC studies find that non-Arrhenius behaviour, characteristic of pristine MBBA and a manifestation of non-equilibrium nature [Dan et al., J. Chem. Phys. 143, 094501 (2015)], is preserved in presence of entropic screening in the hexane solution, while it changes to Arrhenius behaviour (signifying equilibrium behaviour) in presence of enthalpic screening in methanol solution. FTIR spectra show similar dependence on the solvent induced screening in the intensities of the imine (—C = N) stretch and the out-of-plane distortion vibrations of the benzene rings of MBBA with hexane and methanol as in DSC, further establishing our entropic and enthalpic screening models. UV-Vis spectra of the electronic transitions in MBBA as a function of temperature also exhibit different dependences of intensities on the solvent induced screening, and an exponential decrease is observed in presence of hexane while methanol completely changes the nature of interaction to follow a linear dependence.
Chen, Yunjie; Roux, Benoît
2014-09-21
Hybrid schemes combining the strength of molecular dynamics (MD) and Metropolis Monte Carlo (MC) offer a promising avenue to improve the sampling efficiency of computer simulations of complex systems. A number of recently proposed hybrid methods consider new configurations generated by driving the system via a non-equilibrium MD (neMD) trajectory, which are subsequently treated as putative candidates for Metropolis MC acceptance or rejection. To obey microscopic detailed balance, it is necessary to alter the momentum of the system at the beginning and/or the end of the neMD trajectory. This strict rule then guarantees that the random walk in configurational space generated by such hybrid neMD-MC algorithm will yield the proper equilibrium Boltzmann distribution. While a number of different constructs are possible, the most commonly used prescription has been to simply reverse the momenta of all the particles at the end of the neMD trajectory ("one-end momentum reversal"). Surprisingly, it is shown here that the choice of momentum reversal prescription can have a considerable effect on the rate of convergence of the hybrid neMD-MC algorithm, with the simple one-end momentum reversal encountering particularly acute problems. In these neMD-MC simulations, different regions of configurational space end up being essentially isolated from one another due to a very small transition rate between regions. In the worst-case scenario, it is almost as if the configurational space does not constitute a single communicating class that can be sampled efficiently by the algorithm, and extremely long neMD-MC simulations are needed to obtain proper equilibrium probability distributions. To address this issue, a novel momentum reversal prescription, symmetrized with respect to both the beginning and the end of the neMD trajectory ("symmetric two-ends momentum reversal"), is introduced. Illustrative simulations demonstrate that the hybrid neMD-MC algorithm robustly yields a correct
Effect of Non-Equilibrium Surface Thermochemistry in Simulation of Carbon Based Ablators
NASA Technical Reports Server (NTRS)
Chen, Yih-Kanq; Gokcen, Tahir
2012-01-01
This study demonstrates that coupling of a material thermal response code and a flow solver using non-equilibrium gas/surface interaction model provides time-accurate solutions for the multidimensional ablation of carbon based charring ablators. The material thermal response code used in this study is the Two-dimensional Implicit Thermal-response and AblatioN Program (TITAN), which predicts charring material thermal response and shape change on hypersonic space vehicles. Its governing equations include total energy balance, pyrolysis gas mass conservation, and a three-component decomposition model. The flow code solves the reacting Navier-Stokes equations using Data Parallel Line Relaxation (DPLR) method. Loose coupling between the material response and flow codes is performed by solving the surface mass balance in DPLR and the surface energy balance in TITAN. Thus, the material surface recession is predicted by finite-rate gas/surface interaction boundary conditions implemented in DPLR, and the surface temperature and pyrolysis gas injection rate are computed in TITAN. Two sets of nonequilibrium gas/surface interaction chemistry between air and the carbon surface developed by Park and Zhluktov, respectively, are studied. Coupled fluid-material response analyses of stagnation tests conducted in NASA Ames Research Center arc-jet facilities are considered. The ablating material used in these arc-jet tests was Phenolic Impregnated Carbon Ablator (PICA). Computational predictions of in-depth material thermal response and surface recession are compared with the experimental measurements for stagnation cold wall heat flux ranging from 107 to 1100 Watts per square centimeter.
Non-equilibrium phase map, optical and electrical properties of Cu-Zn-O alloys
NASA Astrophysics Data System (ADS)
Subramaniyan, Archana; Perkins, John; O'Hayre, Ryan; Ginley, David; Lany, Stephan; Zakutayev, Andriy
2014-03-01
Cuprous oxide (Cu2O) is a candidate p-type solar cell absorber material that has been spotlighted recently due to its low cost, earth abundant and non-toxic nature. The maximum reported efficiency of Cu2O based solar cells is rather low (5. 38%) and it can in part be attributed its forbidden direct band gap (2.1 eV) and higher absorption threshold (2.6 eV). Here, we alloy Cu2O with ZnO via combinatorial RF magnetron sputtering as a function of temperature (T) and composition at fixed 20 mTorr Ar pressure to modify the electronic band structure and reduce its absorption threshold, which can potentially enhance the solar cell performance. A non-equilibrium Cu-Zn-O phase map was generated in the T range 100 - 400 °C and Zn composition 0 - 37 at%. Highly crystalline Cu2O structured Cu-Zn-O alloys with Zn content of 0 to 17 at% were synthesized in the T range 200 - 270 °C. With increasing Zn at%, the preferential orientation in Cu-Zn-O alloy changes from (200) to (111) direction. At lower T (<200 °C), either amorphous or poor crystalline Cu2O structured alloys were observed, whereas at higher T (>270 ° C) and higher Zn composition (>25 at%), CuO or ZnO second phases were observed. The absorption coefficient of all Cu-Zn-O alloys was higher than that of phase pure Cu2O. The absorption threshold () was also reduced significantly, for example, at = 2*104 cm-1 the absorption threshold of Cu-Zn-O alloy with 10 at% Zn reduced from 2.4 eV to 2.1 eV. The electrical conductivity of all Cu-Zn-O alloys was measured to be within 2 - 5 mS/cm.
Radiation efficiency of earthquake sources at different hierarchical levels
Kocharyan, G. G.
2015-10-27
Such factors as earthquake size and its mechanism define common trends in alteration of radiation efficiency. The macroscopic parameter that controls the efficiency of a seismic source is stiffness of fault or fracture. The regularities of this parameter alteration with scale define several hierarchical levels, within which earthquake characteristics obey different laws. Small variations of physical and mechanical properties of the fault principal slip zone can lead to dramatic differences both in the amplitude of released stress and in the amount of radiated energy.
Method and system for imaging a radiation source
Myjak, Mitchell J [Richland, WA; Seifert, Carolyn E [Kennewick, WA; Morris, Scott J [Kennewick, WA
2011-04-19
A method for imaging a radiation source, and a device that utilizes these methods that in one embodiment include the steps of: calculating at least one Compton cone of a first parameter of a radiation emission from information received from a sensor occurrence; and tracing this Compton cone on to a unit sphere having preselected characteristics using an estimated angular uncertainty to limit at least a portion of said tracing. In another embodiment of the invention at least two Compton cones are calculated and then intersected upon a predefined surface such as a sphere. These intersection points can then be iterated over a preselected series of prior events.
Preconceptual design requirements for the X-1 Advanced Radiation Source
Rochau, G.E.; Hands, J.A.; Raglin, P.S.; Ramirez, J.J.; Goldstein, S.A.; Cereghino, S.J.; MacLeod, G.
1998-09-01
The X-1 Advanced Radiation Source represents the next step in providing the US Department of Energy`s Stockpile Stewardship Program with the high-energy, large volume, laboratory x-ray source for the Radiation Effects Science and Simulation, Inertial Confinement Fusion, and Weapon Physics Programs. Advances in fast pulsed power technology and in z-pinch hohlraums on Sandia National Laboratories` Z Accelerator provide sufficient basis for pursuing the development of X-1. The X-1 plan follows a strategy based on scaling the 2 MJ x-ray output on Z via a 3-fold increase in z-pinch load current. The large volume (>5 cm{sup 3}), high temperature (>150 eV), temporally long (>10 ns) hohlraums are unique outside of underground nuclear weapon testing. Analytical scaling arguments and hydrodynamic simulations indicate that these hohlraums at temperatures of 230--300 eV will ignite thermonuclear fuel and drive the reaction to a yield of 200 to 1,000 MJ in the laboratory. X-1 will provide the high-fidelity experimental capability to certify the survivability and performance of non-nuclear weapon components in hostile radiation environments. Non-ignition sources will provide cold x-ray environments (<15 keV), and high yield fusion burn sources will provide high fidelity warm x-ray environments (15 keV--80 keV).
Handling radiation generated during an ion source commissioning
Ren, H. T.; Zhao, J. Peng, S. X.; Lu, P. N.; Zhou, Q. F.; Xu, Y.; Chen, J.; Zhang, T.; Zhang, A. L.; Guo, Z. Y.; Chen, J. E.
2014-02-15
Radiation is an important issue, which should be carefully treated during the design and commissioning of an ion source. Measurements show that X-rays are generated around the ceramics column of an extraction system when the source is powered up to 30 kV. The X-ray dose increases greatly when a beam is extracted. Inserting the ceramic column into a metal vacuum box is a good way to block X-ray emission for those cases. Moreover, this makes the online test of an intense H{sup +} ion beam with energy up to 100 keV possible. However, for deuteron ion source commissioning, neutron and gamma-ray radiation become a serious topic. In this paper, we will describe the design of the extraction system and the radiation doses of neutrons and gamma-rays measured at different D{sup +} beam energy during our 2.45 GHz deuteron electron cyclotron resonance ion source commissioning for PKUNIFTY (PeKing University Neutron Imaging FaciliTY) project at Peking University.
Handling radiation generated during an ion source commissioning
NASA Astrophysics Data System (ADS)
Ren, H. T.; Zhao, J.; Peng, S. X.; Lu, P. N.; Zhou, Q. F.; Xu, Y.; Chen, J.; Zhang, T.; Zhang, A. L.; Guo, Z. Y.; Chen, J. E.
2014-02-01
Radiation is an important issue, which should be carefully treated during the design and commissioning of an ion source. Measurements show that X-rays are generated around the ceramics column of an extraction system when the source is powered up to 30 kV. The X-ray dose increases greatly when a beam is extracted. Inserting the ceramic column into a metal vacuum box is a good way to block X-ray emission for those cases. Moreover, this makes the online test of an intense H+ ion beam with energy up to 100 keV possible. However, for deuteron ion source commissioning, neutron and gamma-ray radiation become a serious topic. In this paper, we will describe the design of the extraction system and the radiation doses of neutrons and gamma-rays measured at different D+ beam energy during our 2.45 GHz deuteron electron cyclotron resonance ion source commissioning for PKUNIFTY (PeKing University Neutron Imaging FaciliTY) project at Peking University.
Fenwick, John D; Kumar, Sudhir; Scott, Alison J D; Nahum, Alan E
2013-05-01
The dose imparted by a small non-equilibrium photon radiation field to the sensitive volume of a detector located within a water phantom depends on the density of the sensitive volume. Here this effect is explained using cavity theory, and analysed using Monte Carlo data calculated for schematically modelled diamond and Pinpoint-type detectors. The combined impact of the density and atomic composition of the sensitive volume on its response is represented as a ratio, Fw,det, of doses absorbed by equal volumes of unit density water and detector material co-located within a unit density water phantom. The impact of density alone is characterized through a similar ratio, Pρ -, of doses absorbed by equal volumes of unit and modified density water. The cavity theory is developed by splitting the dose absorbed by the sensitive volume into two components, imparted by electrons liberated in photon interactions occurring inside and outside the volume. Using this theory a simple model is obtained that links Pρ - to the degree of electronic equilibrium, see, at the centre of a field via a parameter Icav determined by the density and geometry of the sensitive volume. Following the scheme of Bouchard et al (2009 Med. Phys. 36 4654-63) Fw,det can be written as the product of Pρ -, the water-to-detector stopping power ratio [L[overline](Δ)/ρ](w)(det), and an additional factor Pfl -. In small fields [L[overline](Δ)/ρ](w)(det) changes little with field-size; and for the schematic diamond and Pinpoint detectors Pfl - takes values close to one. Consequently most of the field-size variation in Fw,det originates from the Pρ - factor. Relative changes in see and in the phantom scatter factor sp are similar in small fields. For the diamond detector, the variation of Pρ - with see (and thus field-size) is described well by the simple cavity model using an Icav parameter in line with independent Monte Carlo estimates. The model also captures the overall field-size dependence of P
Requirements and limitations on beam quality in synchrotron radiation sources
Cornacchia, M.
1989-07-01
The requirements and limitations of the third generation of synchrotron radiation facilities are reviewed. These machines are designed to emit radiation of very high intensity, extreme brightness, very short pulses, and laserlike coherence. These performance goals put severe requirements on the quality of the electron or positron beams. Phenomena affecting the injection process and the beam lifetime are discussed. Gas desorption by synchrotron radiation, collective effects (coupled bunch oscillations) and ion trapping (for an electron beam) play an important role. Low emittance lattices are more sensitive to quadrupole movements and at the same time, in order not to lose the benefits of high brilliance, require tighter tolerances on the allowed movement of the photon beam source. 22 refs., 9 figs.
Natural radiation sources, including some lessons for nuclear waste management
NASA Astrophysics Data System (ADS)
Métivier, Henri
2002-09-01
The average effective dose at the global level is, according to UNSCEAR, estimated to be 2.4 mSv from naturally occurring sources. This average value can be divided as follows: 1.3 mSv associated with radon, 0.39 mSv from cosmic radiation, 0.46 mSv from terrestrial radiation, and 0.23 mSv from internal radiation, radon excluded. These values can vary quite significantly depending on the place of habitation. Despite this large variation, no sound epidemiological study has yet shown the health effects on the most exposed populations, apart from a few studies concerning radon, but in which the predominant role of tobacco is difficult to determine. To cite this article: H. Métivier, C. R. Physique 3 (2002) 1035-1048.
Ramaswamy, Rajesh; Sbalzarini, Ivo F; González-Segredo, Nélido
2011-01-28
Stochastic effects from correlated noise non-trivially modulate the kinetics of non-linear chemical reaction networks. This is especially important in systems where reactions are confined to small volumes and reactants are delivered in bursts. We characterise how the two noise sources confinement and burst modulate the relaxation kinetics of a non-linear reaction network around a non-equilibrium steady state. We find that the lifetimes of species change with burst input and confinement. Confinement increases the lifetimes of all species that are involved in any non-linear reaction as a reactant. Burst monotonically increases or decreases lifetimes. Competition between burst-induced and confinement-induced modulation may hence lead to a non-monotonic modulation. We quantify lifetime as the integral of the time autocorrelation function (ACF) of concentration fluctuations around a non-equilibrium steady state of the reaction network. Furthermore, we look at the first and second derivatives of the ACF, each of which is affected in opposite ways by burst and confinement. This allows discriminating between these two noise sources. We analytically derive the ACF from the linear Fokker-Planck approximation of the chemical master equation in order to establish a baseline for the burst-induced modulation at low confinement. Effects of higher confinement are then studied using a partial-propensity stochastic simulation algorithm. The results presented here may help understand the mechanisms that deviate stochastic kinetics from its deterministic counterpart. In addition, they may be instrumental when using fluorescence-lifetime imaging microscopy (FLIM) or fluorescence-correlation spectroscopy (FCS) to measure confinement and burst in systems with known reaction rates, or, alternatively, to correct for the effects of confinement and burst when experimentally measuring reaction rates.
NASA Astrophysics Data System (ADS)
Jahediesfanjani, Hossein
The major part of the gas in coalbed methane and shale gas reservoirs is stored as the adsorbed gas in the coal and organic materials of the black shale internal surfaces. The sorption sites in both reservoirs are composed of several macropores that contain very small pore sizes. Therefore, the adsorption/desorption is very slow process and follows a non-equilibrium trend. The time-dependency of the sorption process is further affected by the reservoir resident water. Water can diffuse into the matrix and adsorption sites, plug the pores and affect the reservoir gas production. This study presents an experimental and theoretical procedure to investigate the effects of the resident water and time-dependency of the sorption process on coalbed and shale gas primary and enhanced recovery by simultaneous CO 2/N2 injection. Series of the experiments are conducted to construct both equilibrium and non-equilibrium single and multi-component isotherms with the presence of water. A novel and rapid data interpretation technique is developed based on the nonequilibrium adsorption/desorption thermodynamics, mass conservation law, and volume filling adsorption theory. The developed technique is implemented to construct both equilibrium and non-equilibrium multi-component multi-phase isotherms from the early time experimental measurements. The non-equilibrium isotherms are incorporated in the coalbed methane/shale gas reservoir simulations to account for the time-dependency of the sorption process. The experimental results indicate that the presence of water in the sorption system reduces both carbon dioxide and nitrogen adsorption rates. Reduction in the adsorption rate for carbon dioxide is more than nitrogen. The results also indicate that the resident water reduces the adsorption ability of low rank coals more than high rank ones. The results of the multi-component sorption tests indicate that increasing the initial mole fraction of the nitrogen gas in the injected CO2/N2
Coherent nuclear resonant optics for third generation synchrotron radiation sources
Alp, E.E.; Mooney, T.M.; Toellner, T.; Homma, H.; Kentjana, M.
1992-06-01
The insertion-device-based, third-generation, synchrotron radiation sources now under construction in Europe, the USA, and Japan bring new opportunities and challenges in the design and manufacture of x-ray optics. These high brightness sources provide new opportunities to overcome some of the outstanding problems associated with nuclear resonant monochromatization of synchrotron radiation. New methods such as polarizing monochromators, and zone plates provide alternative methods for production of {mu}eV-neV resolution in the hard x-ray regime. The design principles, and characterization, and performance of crystal monochromators and of nuclear coherent scattering optics, including Grazing Incidence Anti Reflection (GIAR) films, multilayers, zone plates, as well as single crystals are discussed.
Calculations for Tera-Hertz (THZ) Radiation Sources
Hussein, Yasser A.; Spencer, James E.; /SLAC
2005-06-07
We explore possibilities for THz sources from 0.3-30 THz. While still inaccessible, this broad gap is even wider for advanced acceleration schemes extending from X or, at most, W band RF at the low end up to CO{sub 2} lasers. While the physical implementations of these two approaches are quite different, both are proving difficult to develop so that lower frequency, superconducting RF is currently preferred. Similarly, the validity of modeling techniques varies greatly over this range of frequencies but generally mandates coupling Maxwell's equations to the appropriate device transport physics for which there are many options. Here we study radiation from undulatory-shaped transmission lines using finite-difference, time-domain (FDTD) simulations. Also, we present Monte-Carlo techniques for pulse generation. Examples of THz sources demonstrating coherence are shown with the goal of optimizing on-chip THz radiators for applications that may lead to accelerators.
Isis 1 observations at the source of auroral kilometric radiation
NASA Technical Reports Server (NTRS)
Benson, R. F.; Calvert, W.
1979-01-01
Observations of auroral kilometric radiation (AKR) were made by Isis 1 in the source region. The radiation is found to be generated in the extraordinary mode just above the local cut-off frequency and to emanate nearly perpendicular to the magnetic field. It occurs within local depletions of electron density, where the ratio of plasma frequency to cyclotron frequency is less than 0.2. The density depletion is restricted to altitudes above about 2000 km, and the upper AKR frequency limit corresponds to the extraordinary cut-off frequency at this altitude. AKR is observed from Isis 1 above the nighttime auroral zone over a wider extent in longitude than in latitude with an intense source region observed most often near 2200 LMT and 70 deg invariant latitude. It is directly related to inverted V electron precipitation events with an electron-to-wave energy conversion efficiency of the order of 0.1 to 1%.
Source term calculations for assessing radiation dose to equipment
Denning, R.S.; Freeman-Kelly, R.; Cybulskis, P.; Curtis, L.A.
1989-07-01
This study examines results of analyses performed with the Source Term Code Package to develop updated source terms using NUREG-0956 methods. The updated source terms are to be used to assess the adequacy of current regulatory source terms used as the basis for equipment qualification. Time-dependent locational distributions of radionuclides within a containment following a severe accident have been developed. The Surry reactor has been selected in this study as representative of PWR containment designs. Similarly, the Peach Bottom reactor has been used to examine radionuclide distributions in boiling water reactors. The time-dependent inventory of each key radionuclide is provided in terms of its activity in curies. The data are to be used by Sandia National Laboratories to perform shielding analyses to estimate radiation dose to equipment in each containment design. See NUREG/CR-5175, Beta and Gamma Dose Calculations for PWR and BWR Containments.'' 6 refs., 11 tabs.
Blackbody radiation sources for the IR spectral range
Ogarev, S. A.; Morozova, S. P.; Katysheva, A. A.; Lisiansky, B. E.; Samoylov, M. L.
2013-09-11
Metrological radiometric facilities for optoelectronic instruments calibration utilize in terms of standards as radiation detectors in a form of cryogenic radiometers (CR), so as radiation sources. However in practice, there are no CR working within IR spectral range. An alternative way of radiometric calibration in middle and far IR ranges is to develop a parametric series of standard radiation sources - blackbody (BB) models. The paper describes some of BBs developed at VNIIOFI for the last time [1] from cryogenic (80 K to 200 K), to low (about 200 K to 400 K) and medium (400 K to 700 K) temperature regions for calibration of the IR instruments under cryogenic-vacuum conditions. These BBs are presented by models of both types: variable-temperature and based on fixed points of Ga or In. BBs are characterized with high temperature uniformity and stability. Copper and aluminum alloys are used as the radiation cavity materials. The required value of emissivity ε{sub λ} is achieved by using different black coatings. Low-temperature and cryogenic BBs are based on the principles of indirect multi-zone electric heating (with heat isolation from LN2 cooling loop, or by using an external liquid thermostat with circulating heat-transfer agent. The principles of operation, design and test results of BBs are described.
Cosmic Radiation Fields: Sources in the early Universe
NASA Astrophysics Data System (ADS)
Raue, Martin; Kneiske, Tanja; Horns, Dieter; Elsaesser, Dominik; Hauschildt, Peter
The workshop "Cosmic Radiation Fields - Sources in the Early Universe" (CRF 2010) focuses on the connection between the extragalactic infrared background and sources in the early universe, in particular stars powered by dark matter burning (Dark Stars; DS). The workshop covers the following topics: the cosmic infrared background, formation of early stars, dark stars, effect of dark matter in the early universe, dark matter halos, primordial star formation rate, and reionization. Further information can be found on the conference webpage: http://www.desy.de/crf2010/. Organizing committee: Tanja Kneiske, Martin Raue, Dominik Elsaesser, Alexander Gewering-Peine, Peter Hausschildt, Dieter Horns, and Andreas Maurer.
Transition radiation very soft X-ray source
NASA Astrophysics Data System (ADS)
Umiastowski, K.; Nguyen, A.
1994-05-01
There is a growing interest in the transition radiation (TR), as a soft X-ray source, in the last few years. Many papers have been published on calculations or experiments in the 1-10 keV X-ray energy range using 50-200 MeV electron accelerators. We investigate the possibility to generate very soft X-rays (λ = 12 nm) with low-energy electron accelerator (5-20 MeV). Very little information is available on TR in this range of photon wavelength and electron energy. A stack of 20 foils of beryllium placed in vacuum was used in our computer simulation. Calculation shows that for 1 mA electron beam current, radiation with few mW intensity can be produced. Emitted photons are quasi-monoenergetic (FWHM less than 5%), and well collimated. The aim of our study is to investigate the possibility of fabricate a soft X-ray source, much more compact than synchrotron source and producing an intense and quasi-coherent radiation, for industrial applications.
Radiation damage problems in high power spallation neutron sources
NASA Astrophysics Data System (ADS)
Ullmaier, H.; Carsughi, F.
1995-08-01
In planning the next generation of spallation sources with proton beam powers of several MW (as, for example, the European Spallation Source, ESS), it was soon recognized that materials' degradation by radiation damage will be the most problematic factor in determining the efficiency, lifetime and availability of high power spallation targets. This article gives a short introduction to the physics of radiation damage in metals and points out the differences in the irradiation conditions for materials in fission, fusion and spallation environments, respectively. Based on the expected displacement damage (dpa), hydrogen and helium production, temperatures and stresses we then attempt to identify the critical radiation damage effects for target, window and structural materials. The following compilation of data on proton irradiation of candidate materials (Ta, W, Al and their alloys) shows that the present data base is by far too narrow for materials' selection or lifetime predictions. Since such information is urgently needed for conceptual designs, further investigations are planned beginning with the examination (mechanical tests and TEM in hot cells) of already irradiated specimens: a Ta target assembly removed recently from ISIS at RAL; steel and Al beam windows and TEM specimens irradiated in LANL and PSI, respectively. Parallel to these efforts new irradiations are foreseen in a dual beam facility, in ISOLDE at CERN, and in the spallation source SINQ which is expected to start operation in 1996.
Radiation doses to insertion devices at the advanced photon source
Moog, E. R.; Den Hartog, P. K.; Semones, E. J.; Job, P. K.
1997-07-01
Dose measurements made on and around the insertion devices (IDs) at the Advanced Photon Source are reported. Attempts are made to compare these dose rates to dose rates that have been reported to cause radiation-induced demagnetization, but comparisons are complicated by such factors as the particular magnet material and the techniques used in its manufacture, the spectrum and type of radiation, and the demagnetizing field seen by the magnet. The spectrum of radiation at the IDs has been measured and found to include a large high-energy (7 GeV) component, at least during some runs. Lead shielding installed immediately upstream of the IDs has been found to decrease the dose to the upstream ends of the IDs. It has almost no effect on the dose to the downstream ends of the IDs, however, since much of the radiation travels through the ID vacuum chamber and cannot be readily shielded. Opening the gaps of the IDs during injection and at other times also helps decrease the radiation exposure.
Radiation doses to insertion devices at the advanced photon source
Moog, E.R.; Den Hartog, P.K.; Semones, E.J.; Job, P.K.
1997-07-01
Dose measurements made on and around the insertion devices (IDs) at the Advanced Photon Source are reported. Attempts are made to compare these dose rates to dose rates that have been reported to cause radiation-induced demagnetization, but comparisons are complicated by such factors as the particular magnet material and the techniques used in its manufacture, the spectrum and type of radiation, and the demagnetizing field seen by the magnet. The spectrum of radiation at the IDs has been measured and found to include a large high-energy (7 GeV) component, at least during some runs. Lead shielding installed immediately upstream of the IDs has been found to decrease the dose to the upstream ends of the IDs. It has almost no effect on the dose to the downstream ends of the IDs, however, since much of the radiation travels through the ID vacuum chamber and cannot be readily shielded. Opening the gaps of the IDs during injection and at other times also helps decrease the radiation exposure. {copyright} {ital 1997 American Institute of Physics.}
Technological challenges of third generation synchrotron radiation sources
Cornacchia, M. ); Winick, H. . Stanford Synchrotron Radiation Lab.)
1990-01-01
New third generation'' synchrotron radiation research facilities are now in construction in France, Italy, Japan, Taiwan and the USA. Designs for such facilities are being developed in several other countries. Third generation facilities are based on storage rings with low electron beam emittance and space for many undulator magnets to produce radiation with extremely high brightness and coherent power. Photon beam from these rings will greatly extend present research capabilities and open up new opportunities in imaging, spectroscopy, structural and dynamic studies and other applications. The technological problems of the third generation of synchrotron radiation facilities are reviewed. These machines are designed to emit radiation of very high intensity, extreme brightness, very short pulses, and partial coherence. These performance goals put severe requirements on the quality of the electron or positron beams. Phenomena affecting the injection process and the beam lifetime are discussed. Gas desorption by synchrotron radiation and collective effects play an important role. Low emittance lattices are more sensitive to quadrupole movements and at the same time, in order not to lose the benefits of high brilliance, require tighter tolerances on the allowed movement of the photon beam source. We discuss some of the ways that should be considered to extend the performance capabilities of the facilities in the future. 14 refs., 1 fig.
Plasma and Radiation Modelling of EUV Sources for Micro Lithography
NASA Astrophysics Data System (ADS)
Kruecken, Thomas
2007-04-01
Future extreme ultraviolet (EUV) lithography will require very high radiation intensities in a narrow wavelength range around 13.5 nm, which is most efficiently emitted as line radiation by highly ionized heavy particles. Currently the most intense EUV sources are based on Xenon or Tin discharges. After having investigated the limits of a hollow cathode triggered Xenon pinch discharge a Laser triggered Tin vacuum spark discharge is favored by Philips Extreme UV. Plasma and radiation properties of these highly transient discharges will be compared. Besides simple MHD-models the ADAS software package has been used to generate important atomic and spectral data of the relevant ion stages. To compute excitation and radiation properties, collisional radiative equilibria of individual ion stages are computed. For many lines opacity effects cannot be neglected. The optical depths, however, allow for a treatment based on escape factors. Due to the rapid change of plasma parameters the abundances of the different ionization stages must be computed dynamically. This requires effective ionization and recombination rates, which can also be supplied by ADAS.
Plasma and Radiation Modelling of EUV Sources for Micro Lithography
Kruecken, Thomas
2007-04-06
Future extreme ultraviolet (EUV) lithography will require very high radiation intensities in a narrow wavelength range around 13.5 nm, which is most efficiently emitted as line radiation by highly ionized heavy particles. Currently the most intense EUV sources are based on Xenon or Tin discharges. After having investigated the limits of a hollow cathode triggered Xenon pinch discharge a Laser triggered Tin vacuum spark discharge is favored by Philips Extreme UV.Plasma and radiation properties of these highly transient discharges will be compared. Besides simple MHD-models the ADAS software package has been used to generate important atomic and spectral data of the relevant ion stages. To compute excitation and radiation properties, collisional radiative equilibria of individual ion stages are computed. For many lines opacity effects cannot be neglected. The optical depths, however, allow for a treatment based on escape factors. Due to the rapid change of plasma parameters the abundances of the different ionization stages must be computed dynamically. This requires effective ionization and recombination rates, which can also be supplied by ADAS.
The non-equilibrium statistical mechanics of a simple geophysical fluid dynamics model
NASA Astrophysics Data System (ADS)
Verkley, Wim; Severijns, Camiel
2014-05-01
Lorenz [1] has devised a dynamical system that has proved to be very useful as a benchmark system in geophysical fluid dynamics. The system in its simplest form consists of a periodic array of variables that can be associated with an atmospheric field on a latitude circle. The system is driven by a constant forcing, is damped by linear friction and has a simple advection term that causes the model to behave chaotically if the forcing is large enough. Our aim is to predict the statistics of Lorenz' model on the basis of a given average value of its total energy - obtained from a numerical integration - and the assumption of statistical stationarity. Our method is the principle of maximum entropy [2] which in this case reads: the information entropy of the system's probability density function shall be maximal under the constraints of normalization, a given value of the average total energy and statistical stationarity. Statistical stationarity is incorporated approximately by using `stationarity constraints', i.e., by requiring that the average first and possibly higher-order time-derivatives of the energy are zero in the maximization of entropy. The analysis [3] reveals that, if the first stationarity constraint is used, the resulting probability density function rather accurately reproduces the statistics of the individual variables. If the second stationarity constraint is used as well, the correlations between the variables are also reproduced quite adequately. The method can be generalized straightforwardly and holds the promise of a viable non-equilibrium statistical mechanics of the forced-dissipative systems of geophysical fluid dynamics. [1] E.N. Lorenz, 1996: Predictability - A problem partly solved, in Proc. Seminar on Predictability (ECMWF, Reading, Berkshire, UK), Vol. 1, pp. 1-18. [2] E.T. Jaynes, 2003: Probability Theory - The Logic of Science (Cambridge University Press, Cambridge). [3] W.T.M. Verkley and C.A. Severijns, 2014: The maximum entropy
NASA Astrophysics Data System (ADS)
Peluso, F.; Arienzo, I.
Experimental investigation of the behavior of porous media is a field of interest of modern non-equilibrium thermodynamics. In the frame of a multi-disciplinary re- search project we are performing in our laboratory experimental tests to measure equilibrium and nonequilibrium thermodynamic properties of natural porous media. Aim of our study is to characterize some stone samples and to verify whether a mass transport due to coupled pressure and temperature gradients (thermo-mechanic) is ap- preciable in this kind of porous medium. We have designed an apparatus that allows to measure the volume flux across a porous sample at various, predefined pressures and temperatures, both in isothermal and non isothermal conditions. A mechanical piston compels a liquid to flow through the sample, previously saturated under vacuum with the same fluid. Knowing the geometrical dimensions of the stone, the volume flux is estimated by measuring the time needed to a known amount of liquid to flow across the sample. Measurements have been performed in isothermal conditions at various temperatures and in non-isothermal conditions. Non-isothermal measurements have been performed both in unsteady and steady-state thermal conditions. Before to be undergone to a measurement cycle, samples are dried and weighted. Then they are sat- urated under vacuum with pure distilled water and weighted once again. By difference between the two measurements, porosity is determined. In all examined samples the volume flux has been found linear with respect to the applied pressure at the various temperatures. The values of volume flux in unsteady thermal conditions are consid- erably higher than the one obtained at the same pressure in isothermal conditions at the higher temperature (T=+45rC). This could be the evidence of a thermo-mechanic effect, pushing the water from hot to cold. Once the steady thermal state is reached, however, this effect disappears. Only measurements performed in unsteady thermal
NASA Astrophysics Data System (ADS)
Fan, Zhengfeng; Liu, Jie; Liu, Bin; Yu, Chengxin; He, X. T.
2016-01-01
Fusion ignition experiments on the National Ignition Facility have demonstrated >5 keV hot spot with ρRh lower than 0.3 g/cm2 [Döppner et al., Phys. Rev. Lett. 115, 055001 (2015)]. We present an ion-electron non-equilibrium model, in which the hot-spot ion temperature is higher than its electron temperature so that the hot-spot nuclear reactions are enhanced while energy leaks are considerably reduced. Theoretical analysis shows that the ignition region would be significantly enlarged in the hot-spot ρR-T space as compared with the commonly used equilibrium model. Simulations show that shocks could be utilized to create and maintain non-equilibrium conditions within the hot spot, and the hot-spot ρR requirement is remarkably reduced for achieving self-heating.