Maia, Alex S C; Nascimento, Sheila T; Nascimento, Carolina C N; Gebremedhin, Kifle G
2016-05-01
The effects of air temperature and relative humidity on thermal equilibrium of goats in a tropical region was evaluated. Nine non-pregnant Anglo Nubian nanny goats were used in the study. An indirect calorimeter was designed and developed to measure oxygen consumption, carbon dioxide production, methane production and water vapour pressure of the air exhaled from goats. Physiological parameters: rectal temperature, skin temperature, hair-coat temperature, expired air temperature and respiratory rate and volume as well as environmental parameters: air temperature, relative humidity and mean radiant temperature were measured. The results show that respiratory and volume rates and latent heat loss did not change significantly for air temperature between 22 and 26°C. In this temperature range, metabolic heat was lost mainly by convection and long-wave radiation. For temperature greater than 30°C, the goats maintained thermal equilibrium mainly by evaporative heat loss. At the higher air temperature, the respiratory and ventilation rates as well as body temperatures were significantly elevated. It can be concluded that for Anglo Nubian goats, the upper limit of air temperature for comfort is around 26°C when the goats are protected from direct solar radiation. PMID:27157333
Understanding thermal equilibrium through activities
NASA Astrophysics Data System (ADS)
Pathare, Shirish; Huli, Saurabhee; Nachane, Madhura; Ladage, Savita; Pradhan, Hemachandra
2015-03-01
Thermal equilibrium is a basic concept in thermodynamics. In India, this concept is generally introduced at the first year of undergraduate education in physics and chemistry. In our earlier studies (Pathare and Pradhan 2011 Proc. episteme-4 Int. Conf. to Review Research on Science Technology and Mathematics Education pp 169-72) we found that students in India have a rather unsatisfactory understanding of thermal equilibrium. We have designed and developed a module of five activities, which are presented in succession to the students. These activities address the students’ alternative conceptions that underlie their lack of understanding of thermal equilibrium and aim at enhancing their understanding of the concept.
Understanding Thermal Equilibrium through Activities
ERIC Educational Resources Information Center
Pathare, Shirish; Huli, Saurabhee; Nachane, Madhura; Ladage, Savita; Pradhan, Hemachandra
2015-01-01
Thermal equilibrium is a basic concept in thermodynamics. In India, this concept is generally introduced at the first year of undergraduate education in physics and chemistry. In our earlier studies (Pathare and Pradhan 2011 "Proc. episteme-4 Int. Conf. to Review Research on Science Technology and Mathematics Education" pp 169-72) we…
Thermal equilibrium in Einstein's elevator.
Sánchez-Rey, Bernardo; Chacón-Acosta, Guillermo; Dagdug, Leonardo; Cubero, David
2013-05-01
We report fully relativistic molecular-dynamics simulations that verify the appearance of thermal equilibrium of a classical gas inside a uniformly accelerated container. The numerical experiments confirm that the local momentum distribution in this system is very well approximated by the Jüttner function-originally derived for a flat spacetime-via the Tolman-Ehrenfest effect. Moreover, it is shown that when the acceleration or the container size is large enough, the global momentum distribution can be described by the so-called modified Jüttner function, which was initially proposed as an alternative to the Jüttner function. PMID:23767501
Concept Maps about Chemical Equilibrium and Students' Achievement Scores.
ERIC Educational Resources Information Center
Wilson, Jan
1996-01-01
Examines relationships between structural characteristics of students' concept maps about chemical equilibrium and independent measures of their achievement in chemistry. Results indicate significant relationships between multidimensional scaling coordinates and test scores of recall of knowledge and its application and also reveal structural…
Thermal equilibrium of two quantum Brownian particles
Valente, D. M.; Caldeira, A. O.
2010-01-15
The influence of the environment in the thermal equilibrium properties of a bipartite continuous variable quantum system is studied. The problem is treated within a system-plus-reservoir approach. The considered model reproduces the Brownian motion when the two particles are isolated and induces an effective interaction between them, depending on the choice of the spectral function of the bath. The coupling between the system and the environment guarantees the translational invariance of the system in the absence of an external potential. The entanglement between the particles is measured by the logarithmic negativity, which is shown to monotonically decrease with the increase of the temperature. A range of finite temperatures is found in which entanglement is still induced by the reservoir.
Dynamics of Charged Particles in an Adiabatic Thermal Beam Equilibrium
NASA Astrophysics Data System (ADS)
Chen, Chiping; Wei, Haofei
2010-11-01
Charged-particle motion is studied in the self-electric and self-magnetic fields of a well-matched, intense charged-particle beam and an applied periodic solenoidal magnetic focusing field. The beam is assumed to be in a state of adiabatic thermal equilibrium. The phase space is analyzed and compared with that of the well-known Kapchinskij-Vladimirskij (KV)-type beam equilibrium. It is found that the widths of nonlinear resonances in the adiabatic thermal beam equilibrium are narrower than those in the KV-type beam equilibrium. Numerical evidence is presented, indicating almost complete elimination of chaotic particle motion in the adiabatic thermal beam equilibrium.
Network representations of knowledge about chemical equilibrium: Variations with achievement
NASA Astrophysics Data System (ADS)
Wilson, Janice M.
This study examined variation in the organization of domain-specific knowledge by 50 Year-12 chemistry students and 4 chemistry teachers. The study used nonmetric multidimensional scaling (MDS) and the Pathfinder network-generating algorithm to investigate individual and group differences in student concepts maps about chemical equilibrium. MDS was used to represent the individual maps in two-dimensional space, based on the presence or absence of paired propositional links. The resulting separation between maps reflected degree of hierarchical structure, but also reflected independent measures of student achievement. Pathfinder was then used to produce semantic networks from pooled data from high and low achievement groups using proximity matrices derived from the frequencies of paired concepts. The network constructed from maps of higher achievers (coherence measure = 0.18, linked pairs = 294, and number of subjects = 32) showed greater coherence, more concordance in specific paired links, more important specific conceptual relationships, and greater hierarchical organization than did the network constructed from maps of lower achievers (coherence measure = 0.12, linked pairs = 552, and number of subjects = 22). These differences are interpreted in terms of qualitative variation in knowledge organization by two groups of individuals with different levels of relative expertise (as reflected in achievement scores) concerning the topic of chemical equilibrium. The results suggest that the technique of transforming paired links in concept maps into proximity matrices for input to multivariate analyses provides a suitable methodology for comparing and documenting changes in the organization and structure of conceptual knowledge within and between individual students.
On the thermalization achieved in the reactions involving superheavy nuclei
NASA Astrophysics Data System (ADS)
Bansal, Rajni
2016-05-01
In the present study, we aim to explore the role of Coulomb potential on the thermalization achieved in the reactions involving superheavy nuclei. Particularly, we shall study the degree of the equilibrium attained in a reaction by the 3D density plots, anisotropy ratio as well as by the rapidity distribution of the nucleons. Our study reveals that the degree of the equilibrium attained in the central reactions of the superheavy nuclei remains unaffected by the Coulomb potential.
Concept maps about chemical equilibrium and students' achievement scores
NASA Astrophysics Data System (ADS)
Wilson, Jan
1996-06-01
The purpose of this study was to examine relationships between structural characteristics of students' concept maps about chemical equilibrium and independent measures of their achievement in chemistry. Fifty students in 1991 and seventy students in 1992 completed a concept-mapping task using twenty-four specified concepts. Using similarities in concept map structure, based on the presence or absence of linked pairs of concepts, non-metric multidimensional scaling (MDS) was used to plot the location of the concept maps in coordinate space. The distribution of maps was based on differences in their structure, but also reflected levels of student achievement on independent tests. The relationship between the coordinate location of each student's maps and his or her test scores on independent chemistry achievement tests was sought by canonical correlation analysis of the 1991 data set. This revealed significant relationships between the MDS coordinates and test scores of recall of knowledge and its application. Multiple regression analysis of sixty-one students' maps from the 1992 data set against their percentile rank scores on a national chemistry quiz revealed significant relationships. The results are interpreted as revealing structural differences in conceptual organisation about chemical equilibrium among students with different levels of achievement and thus relative expertise in the domain. The significant relationship between map structure and cognitive process scores in chemistry also supports the view that the organisation of declarative knowledge influences its accessibility in cognitive tasks.
Thermal Equilibrium in Plastic and Glass Microscale Containers
ERIC Educational Resources Information Center
Curbelo, Estela; Cerda, Maria F.; Mendez, Eduardo
2007-01-01
The study describes the various thermal equilibrium conditions, which should be taken care for while designing or selecting the plastic and glass microscale containers for physical chemistry experiments. The results show that the thermal equilibrium completely depends on the material of the container for the same volume and thickness.
Typicality of Thermal Equilibrium and Thermalization in Isolated Macroscopic Quantum Systems
NASA Astrophysics Data System (ADS)
Tasaki, Hal
2016-06-01
Based on the view that thermal equilibrium should be characterized through macroscopic observations, we develop a general theory about typicality of thermal equilibrium and the approach to thermal equilibrium in macroscopic quantum systems. We first formulate the notion that a pure state in an isolated quantum system represents thermal equilibrium. Then by assuming, or proving in certain classes of nontrivial models (including that of two bodies in thermal contact), large-deviation type bounds (which we call thermodynamic bounds) for the microcanonical ensemble, we prove that to represent thermal equilibrium is a typical property for pure states in the microcanonical energy shell. We believe that the typicality, along with the empirical success of statistical mechanics, provides a sound justification of equilibrium statistical mechanics. We also establish the approach to thermal equilibrium under two different assumptions; one is that the initial state has a moderate energy distribution, and the other is the energy eigenstate thermalization hypothesis.
Observing the Casimir-Lifshitz force out of thermal equilibrium
NASA Astrophysics Data System (ADS)
Bimonte, Giuseppe
2015-09-01
The thermal Casimir-Lifshitz force between two bodies held at different temperatures displays striking features that are absent in systems in thermal equilibrium. The manifestation of this force has been observed so far only in Bose-Einstein condensates close to a heated substrate, but never between two macroscopic bodies. Observation of the thermal Casimir-Lifshitz force out of thermal equilibrium with conventional Casimir setups is very difficult because for experimentally accessible separations the thermal force is small compared to the zero-temperature quantum Casimir force unless prohibitively large temperature differences among the plates are considered. We describe an apparatus that allows for direct observation of the thermal force out of equilibrium for submicron separations and for moderate temperature differences between the plates.
Thermal Conductivity of Gas Mixtures in Chemical Equilibrium
NASA Technical Reports Server (NTRS)
Brokaw, Richard S.
1960-01-01
The expression for the thermal conductivity of gas mixtures in chemical equilibrium is presented in a simpler and less restrictive form. This new form is shown to be equivalent to the previous equations.
Exploring Chemical and Thermal Non-equilibrium in Nitrogen Arcs
NASA Astrophysics Data System (ADS)
Ghorui, S.; Das, A. K.
2012-12-01
Plasma torches operating with nitrogen are of special importance as they can operate with usual tungsten based refractory electrodes and offer radical rich non-oxidizing high temperature environment for plasma chemistry. Strong gradients in temperature as well as species densities and huge convective fluxes lead to varying degrees of chemical non-equilibrium in associated regions. An axi-symmetric two-temperature chemical non-equilibrium model of a nitrogen plasma torch has been developed to understand the effects of thermal and chemical non-equilibrium in arcs. A 2-D finite volume CFD code in association with a non-equilibrium property routine enabled extraction of steady state self-consistent distributions of various plasma quantities inside the torch under various thermal and chemical non-equilibrium conditions. Chemical non-equilibrium has been incorporated through computation of diffusive and convective fluxes in each finite volume cell in every iteration and associating corresponding thermodynamic and transport properties through the scheme of 'chemical non-equilibrium parameter' introduced by Ghorui et. al. Recombination coefficient data from Nahar et. al. and radiation data from Krey and Morris have been used in the simulation. Results are presented for distributions of temperature, pressure, velocity, current density, electric potential, species densities and chemical non-equilibrium effects. Obtained results are compared with similar results under LTE.
Thermo-chemical dynamics and chemical quasi-equilibrium of plasmas in thermal non-equilibrium
Massot, Marc; Graille, Benjamin; Magin, Thierry E.
2011-05-20
We examine both processes of ionization by electron and heavy-particle impact in spatially uniform plasmas at rest in the absence of external forces. A singular perturbation analysis is used to study the following physical scenario, in which thermal relaxation becomes much slower than chemical reactions. First, electron-impact ionization is investigated. The dynamics of the system rapidly becomes close to a slow dynamics manifold that allows for defining a unique chemical quasi-equilibrium for two-temperature plasmas and proving that the second law of thermodynamics is satisfied. Then, all ionization reactions are taken into account simultaneously, leading to a surprising conclusion: the inner layer for short time scale (or time boundary layer) directly leads to thermal equilibrium. Global thermo-chemical equilibrium is reached within a short time scale, involving only chemical reactions, even if thermal relaxation through elastic collisions is assumed to be slow.
The thermal vacuum for non-equilibrium steady state
NASA Astrophysics Data System (ADS)
Imai, Ryosuke; Kuwahara, Yukiro; Nakamura, Yusuke; Yamanaka, Yoshiya
Our purpose is to construct a theoretical description of non-equilibrium steady state (NESS), employing thermo field dynamics (TFD). TFD is the operator-based formalism of thermal quautum field theory, where every degree of freedom is doubled and thermal averages are given by expectation values of the thermal vacuum. To specify the thermal vacuum for NESS is a non-trivial issue, and we attempt it on the analogy between the superoperator formalism and TFD. Using the thermal vacuum thus obtained, we analyze the NESS which is realized in the two-reservoir model. It will be shown that the NESS vacuum of the model coincides with the fixed point solutions of the quantum transport equation derived by the self-consistent renormalization of the self-energy in non-equilibrium TFD.
On the approach to thermal equilibrium of macroscopic quantum systems
Goldstein, Sheldon; Tumulka, Roderich
2011-03-24
In joint work with J. L. Lebowitz, C. Mastrodonato, and N. Zanghi[2, 3, 4], we considered an isolated, macroscopic quantum system. Let H be a micro-canonical 'energy shell', i.e., a subspace of the system's Hilbert space spanned by the (finitely) many energy eigenstates with energies between E and E+{delta}E. The thermal equilibrium macro-state at energy E corresponds to a subspace H{sub eq} of H such that dimHeq/dimH is close to 1. We say that a system with state vector {psi}{epsilon}H is in thermal equilibrium if {psi} is 'close' to H{sub eq}. We argue that for 'typical' Hamiltonians, all initial state vectors {psi}{sub 0} evolve in such a way that {psi}{sub t} is in thermal equilibrium for most times t. This is closely related to von Neumann's quantum ergodic theorem of 1929.
Construction of a Non-Equilibrium Thermal Boundary Layer Facility
NASA Astrophysics Data System (ADS)
Biles, Drummond; Ebadi, Alireza; Ma, Allen; White, Christopher
2015-11-01
A thermally conductive, electrically heated wall-plate forming the bottom wall of a wind tunnel has been constructed and validation tests have been performed. The wall-plate is a sectioned wall design, where each section is independently heated and controlled. Each section consists of an aluminum 6061 plate, an array of resistive heaters affixed to the bottom of the aluminum plate, and a calcium silicate holder used for thermal isolation. Embedded thermocouples in the aluminum plates are used to monitor the wall temperature and for feedback control of wall heating. The wall-plate is used to investigate thermal transport in both equilibrium and non-equilibrium boundary layers. The non-equilibrium boundary layer flow investigated is oscillatory flow produced by a rotor-stator mechanism placed downstream of the test section of the wind tunnel.
Quantum systems in a stationary environment out of thermal equilibrium
NASA Astrophysics Data System (ADS)
Bellomo, Bruno; Messina, Riccardo; Felbacq, Didier; Antezza, Mauro
2013-01-01
We discuss how the thermalization of an elementary quantum system is modified when the system is placed in an environment out of thermal equilibrium. To this aim we provide a detailed investigation of the dynamics of an atomic system placed close to a body of arbitrary geometry and dielectric permittivity, whose temperature TM is different from that of the surrounding walls TW. A suitable master equation for the general case of an N-level atom is first derived and then specialized to the cases of a two- and three-level atom. Transition rates and steady states are explicitly expressed as a function of the scattering matrices of the body and become both qualitatively and quantitatively different from the case of radiation at thermal equilibrium. Out of equilibrium, the system steady state depends on the system-body distance, on the geometry of the body, and on the interplay of all such parameters with the body optical resonances. While a two-level atom tends toward a thermal state, this is not the case already in the presence of three atomic levels. This peculiar behavior can be exploited, for example, to invert the populations ordering and to provide an efficient cooling mechanism for the internal state of the quantum system. We finally provide numerical studies and asymptotic expressions when the body is a slab of finite thickness. Our predictions can be relevant for a wide class of experimental configurations out of thermal equilibrium involving different physical realizations of two- or three-level systems.
Partition functions and concentrations in plasmas out of thermal equilibrium
Andre, P.
1995-06-01
Taking into account the disequilibrium between the temperatures (electronic, rotational, vibrational, translational) in a nitrogen-plasma out of thermal equilibrium, different partition function and chemical potential calculation method are described and applied. From the variation of the temperature hypotheses, their influence on the plasma concentration is shown.
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.
Thermal Non-Equilibrium Flows in Three Space Dimensions
NASA Astrophysics Data System (ADS)
Zeng, Yanni
2016-01-01
We study the equations describing the motion of a thermal non-equilibrium gas in three space dimensions. It is a hyperbolic system of six equations with a relaxation term. The dissipation mechanism induced by the relaxation is weak in the sense that the Shizuta-Kawashima criterion is violated. This implies that a perturbation of a constant equilibrium state consists of two parts: one decays in time while the other stays. In fact, the entropy wave grows weakly along the particle path as the process is irreversible. We study thermal properties related to the well-posedness of the nonlinear system. We also obtain a detailed pointwise estimate on the Green's function for the Cauchy problem when the system is linearized around an equilibrium constant state. The Green's function provides a complete picture of the wave pattern, with an exact and explicit leading term. Comparing with existing results for one dimensional flows, our results reveal a new feature of three dimensional flows: not only does the entropy wave not decay, but the velocity also contains a non-decaying part, strongly coupled with its decaying one. The new feature is supported by the second order approximation via the Chapman-Enskog expansions, which are the Navier-Stokes equations with vanished shear viscosity and heat conductivity.
Graphical representation for thermal equilibrium when transition temperatures are present
NASA Astrophysics Data System (ADS)
Rojas, Roberto
2016-01-01
We propose the use of graphics in order to get a quick insight of the thermal equilibrium of two bodies, when a transition temperature is present in the interval between both initial temperatures. We have found two convenient variables in order to represent the mathematical condition for the partial or complete transition of each component. In mixing hot water and cold ice, the proposed graphical representation exhibits straight lines separating four regions corresponding to different equilibrium states, going from one containing just ice up to the other containing just water, and two states in between with increased ice or increased water. This graphical representation helps to avoid typical student errors in learning elementary physics.
Thermal equilibrium and statistical thermometers in special relativity.
Cubero, David; Casado-Pascual, Jesús; Dunkel, Jörn; Talkner, Peter; Hänggi, Peter
2007-10-26
There is an intense debate in the recent literature about the correct generalization of Maxwell's velocity distribution in special relativity. The most frequently discussed candidate distributions include the Jüttner function as well as modifications thereof. Here we report results from fully relativistic one-dimensional molecular dynamics simulations that resolve the ambiguity. The numerical evidence unequivocally favors the Jüttner distribution. Moreover, our simulations illustrate that the concept of "thermal equilibrium" extends naturally to special relativity only if a many-particle system is spatially confined. They make evident that "temperature" can be statistically defined and measured in an observer frame independent way. PMID:17995314
Robust Gaussian entanglement with a macroscopic oscillator at thermal equilibrium
NASA Astrophysics Data System (ADS)
Filip, Radim; Kupčík, Vojtěch
2013-06-01
We propose a feasible Gaussian version of the Schrödinger-cat state. We consider it as a robust Gaussian state of an oscillator prepared in a low-energy Gaussian quantum state entangled with another oscillator which was initially in a quantum state at thermal equilibrium with an arbitrary large energy (macroscopic oscillator). To generate it, we suggest two-mode squeezing as the best candidate. We test that the Gaussian version of the Schrödinger-cat state can be also used to remotely prepare a squeezed state of the macroscopic oscillator.
Giri, Ashutosh; Hopkins, Patrick E
2016-02-28
We develop an analytical model for the thermal boundary conductance between a solid and a gas. By considering the thermal fluxes in the solid and the gas, we describe the transmission of energy across the solid/gas interface with diffuse mismatch theory. From the predicted thermal boundary conductances across solid/gas interfaces, the equilibrium thermal accommodation coefficient is determined and compared to predictions from molecular dynamics simulations on the model solid-gas systems. We show that our model is applicable for modeling the thermal accommodation of gases on solid surfaces at non-cryogenic temperatures and relatively strong solid-gas interactions (εsf ≳ kBT). PMID:26931716
Equilibrium statistical-thermal models in high-energy physics
NASA Astrophysics Data System (ADS)
Tawfik, Abdel Nasser
2014-05-01
We review some recent highlights from the applications of statistical-thermal models to different experimental measurements and lattice QCD thermodynamics that have been made during the last decade. We start with a short review of the historical milestones on the path of constructing statistical-thermal models for heavy-ion physics. We discovered that Heinz Koppe formulated in 1948, an almost complete recipe for the statistical-thermal models. In 1950, Enrico Fermi generalized this statistical approach, in which he started with a general cross-section formula and inserted into it, the simplifying assumptions about the matrix element of the interaction process that likely reflects many features of the high-energy reactions dominated by density in the phase space of final states. In 1964, Hagedorn systematically analyzed the high-energy phenomena using all tools of statistical physics and introduced the concept of limiting temperature based on the statistical bootstrap model. It turns to be quite often that many-particle systems can be studied with the help of statistical-thermal methods. The analysis of yield multiplicities in high-energy collisions gives an overwhelming evidence for the chemical equilibrium in the final state. The strange particles might be an exception, as they are suppressed at lower beam energies. However, their relative yields fulfill statistical equilibrium, as well. We review the equilibrium statistical-thermal models for particle production, fluctuations and collective flow in heavy-ion experiments. We also review their reproduction of the lattice QCD thermodynamics at vanishing and finite chemical potential. During the last decade, five conditions have been suggested to describe the universal behavior of the chemical freeze-out parameters. The higher order moments of multiplicity have been discussed. They offer deep insights about particle production and to critical fluctuations. Therefore, we use them to describe the freeze-out parameters
Thermal equilibrium responses in Guzerat cattle raised under tropical conditions.
Camerro, Leandro Zuccherato; Maia, Alex Sandro Campos; Neto, Marcos Chiquitelli; Costa, Cintia Carol de Melo; Castro, Patric André
2016-08-01
The literature is very sparse regarding research on the thermal equilibrium in Guzerat cattle (Bos indicus) under field conditions. Some factors can modify the physiological response of Guzerat cattle, such as the reactivity of these animals to handling. Thus, the development of a methodology to condition and select Guzerat cattle to acclimate them to the routine collection of data without altering their physiological response was the objective of the preliminary experiment. Furthermore, the animals selected were used in the main experiment to determine their thermal equilibrium according to the thermal environment. For this proposal, the metabolic heat production and heat exchange between the animal and the environment were measured simultaneously in the field with an indirect calorimetry system coupled to a facial mask. The results of the preliminary experiment showed that the respiratory rate could demonstrate that conditioning efficiently reduced the reactivity of the animals to experimental handling. Furthermore, the respiratory rate can be used to select animals with less reactivity. The results of the main experiment demonstrate that the skin, hair-coat surface and expired air temperature depend on the air temperature, whereas the rectal temperature depends on the time of day; consequently, the sensible heat flow was substantially reduced from 70 to 20Wm(-2) when the air temperature increased from 24 to 34°C. However, the respiratory latent heat flow increased from 10 to 15Wm(-2) with the same temperature increase. Furthermore, the metabolic heat production remained stable, independent of the variation of the air temperature; however, it was higher in males than in females (by approximately 25%). This fact can be explained by the variation of the ventilation rate, which had a mean value of 1.6 and 2.2Ls(-1) for females and males, respectively. PMID:27503735
Truncated Thermal Equilibrium Distribution for Intense Beam Propagation
Ronald C. Davidson; Hong Qin; Steven M. Lund
2003-02-26
An intense charged-particle beam with directed kinetic energy ({lambda}{sub b}-1)m{sub b}c{sup 2} propagates in the z-direction through an applied focusing field with transverse focusing force modeled by F{sub foc} = -{lambda}{sub b}m{sub b}{omega}{sub beta}{sup 2} {perpendicular} x {perpendicular} in the smooth focusing approximation. This paper examines properties of the axisymmetric, truncated thermal equilibrium distribution F(sub)b(r,p perpendicular) = A exp (-H Perpendicular/T perpendicular (sub)b) = (H perpendicular-E(sub)b), where A, T perpendicular (sub)b, and E (sub)b are positive constants, and H perpendicular is the Hamiltonian for transverse particle motion. The equilibrium profiles for beam number density, n(sub)b(r) = * d{sup 2}pF(sub)b(r,p perpendicular), and transverse temperature, T perpendicular (sub)b(r) = * d{sup 2}p(p{sup 2} perpendicular/2 lambda (sbu)bm (sub)b)F(sub)b(r,p perpendicular), are calculated self-consistently including space-charge effects. Several properties of the equilibrium profiles are noteworthy. For example, the beam has a sharp outer edge radius r(sub)b with n(sub)b(r greater than or equal to rb) = 0, where r(sub)b depends on the value of E(sub)b/T (sub)perpendicular(sub)b. In addition, unlike the choice of a semi-Gaussian distribution, F{sup SG}(sub)b = A exp (-p{sup 2}(sub)perpendicular/2lambda(sub)bm(sub)bTperpendicular(sub)b) = (r-r(sub)b), the truncated thermal equilibrium distribution F(sub)b(r,p) depends on (r,p) only through the single-particle constant of the motion Hperpendiuclar and is therefore a true steady-state solution (*/*t = 0) of the nonlinear Vlasov-Maxwell equations.
Wang Weizong; Rong Mingzhe; Yan, J. D.; Spencer, Joseph W.; Murphy, A. B.
2011-11-15
Calculated thermophysical properties of nitrogen plasmas in and out of thermal equilibrium are presented. The cut-off of the partition functions due to the lowering of the ionization potential has been taken into account, together with the contributions from different core excited electronic states. The species composition and thermodynamic properties are determined numerically using the Newton-Raphson iterative method, taking into account the corrections due to Coulomb interactions. The transport properties including diffusion coefficient, viscosity, thermal conductivity, and electrical conductivity are calculated using the most recent collision interaction potentials by adopting Devoto's electron and heavy particle decoupling approach, expanded to the third-order approximation (second-order for viscosity) in the framework of Chapman-Enskog method. Results are presented in the pressure range of 0.1 atm-10 atm and in electron temperature range from 300 to 40 000 K, with the ratio of electron temperature to heavy-particle temperature varied from 1 to 20. Results are compared with those from previous works, and the influences of different definitions of the Debye length are discussed.
Local Thermal Equilibrium for Certain Stochastic Models of Heat Transport
NASA Astrophysics Data System (ADS)
Li, Yao; Nándori, Péter; Young, Lai-Sang
2016-04-01
This paper is about nonequilibrium steady states (NESS) of a class of stochastic models in which particles exchange energy with their "local environments" rather than directly with one another. The physical domain of the system can be a bounded region of R^d for any d ge 1. We assume that the temperature at the boundary of the domain is prescribed and is nonconstant, so that the system is forced out of equilibrium. Our main result is local thermal equilibrium in the infinite volume limit. In the Hamiltonian context, this would mean that at any location x in the domain, local marginal distributions of NESS tend to a probability with density 1/Z e^{-β (x) H}, permitting one to define the local temperature at x to be β (x)^{-1}. We prove also that in the infinite volume limit, the mean energy profile of NESS satisfies Laplace's equation for the prescribed boundary condition. Our method of proof is duality: by reversing the sample paths of particle movements, we convert the problem of studying local marginal energy distributions at x to that of joint hitting distributions of certain random walks starting from x, and prove that the walks in question become increasingly independent as system size tends to infinity.
Path integral Liouville dynamics for thermal equilibrium systems
NASA Astrophysics Data System (ADS)
Liu, Jian
2014-06-01
We show a new imaginary time path integral based method—path integral Liouville dynamics (PILD), which can be derived from the equilibrium Liouville dynamics [J. Liu and W. H. Miller, J. Chem. Phys. 134, 104101 (2011)] in the Wigner phase space. Numerical tests of PILD with the simple (white noise) Langevin thermostat have been made for two strongly anharmonic model problems. Since implementation of PILD does not request any specific form of the potential energy surface, the results suggest that PILD offers a potentially useful approach for general condensed phase molecular systems to have the two important properties: conserves the quantum canonical distribution and recovers exact thermal correlation functions (of even nonlinear operators, i.e., nonlinear functions of position or momentum operators) in the classical, high temperature, and harmonic limits.
Path integral Liouville dynamics for thermal equilibrium systems
Liu, Jian
2014-06-14
We show a new imaginary time path integral based method—path integral Liouville dynamics (PILD), which can be derived from the equilibrium Liouville dynamics [J. Liu and W. H. Miller, J. Chem. Phys. 134, 104101 (2011)] in the Wigner phase space. Numerical tests of PILD with the simple (white noise) Langevin thermostat have been made for two strongly anharmonic model problems. Since implementation of PILD does not request any specific form of the potential energy surface, the results suggest that PILD offers a potentially useful approach for general condensed phase molecular systems to have the two important properties: conserves the quantum canonical distribution and recovers exact thermal correlation functions (of even nonlinear operators, i.e., nonlinear functions of position or momentum operators) in the classical, high temperature, and harmonic limits.
Determination of Viral Capsid Elastic Properties from Equilibrium Thermal Fluctuations
NASA Astrophysics Data System (ADS)
May, Eric R.; Brooks, Charles L., III
2011-05-01
We apply two-dimensional elasticity theory to viral capsids to develop a framework for calculating elastic properties of viruses from equilibrium thermal fluctuations of the capsid surface in molecular dynamics and elastic network model trajectories. We show that the magnitudes of the long wavelength modes of motion available in a simulation with all atomic degrees of freedom are recapitulated by an elastic network model. For the mode spectra to match, the elastic network model must be scaled appropriately by a factor which can be determined from an icosahedrally constrained all-atom simulation. With this method we calculate the two-dimensional Young’s modulus Y, bending modulus κ, and Föppl-von Kármán number γ, for the T=1 mutant of the Sesbania mosaic virus. The values determined are in the range of previous theoretical estimates.
RF linac designs with beams in thermal equilibrium
NASA Astrophysics Data System (ADS)
Reiser, Martin; Brown, Nathan
1996-06-01
Beams in conventional radio-frequency linear accelerators (rf linacs) usually have a transverse temperature which is much larger than the longitudinal temperature. With high currents, space charge forces couple the transverse and longitudinal particle motions, driving the beam toward thermal equilibrium, which leads to emittance growth and halo formation. A design strategy is proposed in which the beam has equal transverse and longitudinal temperatures through the entire linac, avoiding these undesirable effects. For such equipartitioned linac beams, simple analytical relationships can be derived for the bunch size, tune depression, and other parameters as a function of beam intensity, emittance, and external focusing. These relations were used to develop three conceptual designs for a 938 MeV, 100 mA proton linac with different tune depressions, which are presented in this paper.
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.
Optical stabilization of Rb vapor density above thermal equilibrium
NASA Astrophysics Data System (ADS)
Burchianti, A.; Bogi, A.; Marinelli, C.; Mariotti, E.; Moi, L.
2010-08-01
We stabilize the Rb vapor density above its thermal equilibrium value in sealed glass cells, which are generally used in atomic physics experiments. The method relies on light-induced desorption of Rb atoms from dielectric surfaces. The process does not demand high light intensities so that LEDs or laser diodes can be used as desorbing sources. The experiments are carried out in Pyrex cells either coated with a polydimethylsiloxane film or containing a porous glass sample. Under illumination both the organic coating and the porous sample release a large amount of Rb atoms into the cell volume. We show that the Rb vapor density can be maintained to a preset value, using a desorbing light intensity controlled by a feedback signal given by the Rb absorption or fluorescence level. Moreover, we find that the stabilization technique does not depend on the microscopic mechanisms underlying photodesorption.
Thermal equilibrium of a cryogenic magnetized pure electron plasma
NASA Technical Reports Server (NTRS)
Dubin, D. H. E.; Oneil, T. M.
1986-01-01
The thermal equilibrium correlation properties of a magnetically confined pure electron plasma (McPEP) are related to those of a one-component plasma (OCP). The N-particle spatial distribution rho sub s and the Helmholtz free energy F are evaluated for the McPEP to O(lambda sub d-squared/a-squared), where lambda sub d is the thermal de Broglie wavelength and is an interparticle spacing. The electron gyromotion is allowed to be fully quantized while the guiding center motion is quasi-classical. The distribution rho sub s is shown to be identical to that of a classical OCP with a slightly modified potential. To O(lambda sub d-squared/a-squared) this modification does not affect that part of F that is caused by correlations, as long as certain requirements concerning the size of the plasma are met. This theory is motivated by a current series of experiments that involve the cooling of a magnetically confined pure electron plasma to the cryogenic temperature range.
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.
NASA Astrophysics Data System (ADS)
Morel, Vincent; Bultel, Arnaud
2014-11-01
The Collisional-Radiative model CoRaM-Al is elaborated and implemented in a 0D numerical approach in the purpose of describing the formation of the plasma resulting from the interaction between a τ = 4 ns Nd:YAG laser pulse and an aluminium sample in vacuum. The influence of the four harmonics at 266, 355, 532 and 1064 nm on the behavior of the nascent plasma is studied. In each case, the fluence is set equal to the threshold above which a phase explosion takes place (fluence of 7.7, 7.4, 6.8, 5.1 J cm-2 in order of increasing wavelength). The model takes into account free electrons and excited states of Al, Al+, Al2+ and Al3+. Both groups of particles are characterized by their translation temperature in thermal non-equilibrium. Besides, each population density is assumed to be in chemical non-equilibrium and to behave freely through the involved seven elementary processes (electron impact induced excitation and ionization, elastic collisions, multiphoton ionization, inverse laser Bremsstrahlung, direct thermal Bremsstrahlung and spontaneous emission). Atoms passing from the sample to the gas are described by considering classical vaporization phenomena (governed by the Hertz-Knudsen law) so that the surface temperature is limited to values less than the critical point (Tc = 6700 K). The relative role of the elementary processes is discussed and the time-evolution of the excitation of the species is analyzed for the four considered wavelengths. This study allows to determine the different excitation temperatures as well as their evolution in time. Thus the conditions required for the achievement of the Local Thermodynamic Equilibrium can be precisely described.
A convection modified thermal equilibrium in near-critical fluids under microgravity conditions
NASA Astrophysics Data System (ADS)
Accary, G.; Raspo, I.; Bontoux, P.; Zappoli, B.
As the vapor-liquid critical point is approached in zero-gravity, the time it takes for a near-critical fluid cell to reach thermal equilibrium approaches infinity, which necessitates long duration experiments in space. However in microgravity, the convection modifies the thermal equilibrium due to the high density and the hyper-compressibility of a near-critical fluid. Using three-dimensional direct numerical simulations, the aim of this study is to evaluate, in low-gravity conditions, the contribution of the residual convection in reaching the thermal equilibrium and in structuring the temperature field inside a differentially heated enclosure filled with a near-critical fluid.
Emittance growth from bend straight transitions for beams approaching thermal equilibrium
Barnard, J J; Losic, B
1998-08-19
In certain applications such as heavy ion fusion, intense beams with large space charge tune depressions will be transferred from linear transport sections into bent, transport, sections. In some. designs, such as recircutating induction accelerators, transport. through bends will occur over thousands of betatron periods and in some driver designs the final transports through a bend will occur over tens of betatron periods. Over such distances, non-linear space charge forces are expected to produce particle phase space distributions which are close to thermal equilibrium, especially with respect to lower order moments. Here we calculate the properties of thermal equilibrium beams in bends assuming uniform focusing, as a function of two dimensionless parameters. We also outline the calculation of the change in emittance for a beam that is initially in thermal equilibrium in a straight transport section. and that finally reaches thermal equilibrium in a bent system, using an energy conservation constrint to connect, the two states.
Kikuchi, Takashi; Horioka, Kazuhiko
2009-05-15
Possible emittance growths of intense, nonuniform beams during a transport in a focusing channel are derived as a function of nonlinear field energy and space charge tune depression factors. The nonlinear field energy of the beam with thermal equilibrium distribution is estimated by considering the particle distribution across the cross section of the beam. The results show that the possible emittance growth can be suppressed by keeping the beam particle in thermal equilibrium distribution during the beam transport.
On the relaxation of semi-Gaussian and K-V beams to thermal equilibrium
Lund, S.M.; Barnard, J.J.; Miller, J.M.
1995-05-02
A beam propagating in a continuous, linear focusing channel tends to relax to a thermal equilibrium state. We employ nonlinear conservation constraints to theoretically analyze changes in quantities that characterize both an initial semi-Gaussian beam with a matched rms beam envelope and a K-V beam under a relaxation to thermal equilibrium. Results from particle-in-cell simulations are compared to the theoretical predictions.
Telliez, F; Bach, V; Krim, G; Libert, J P
1997-09-01
A new heating unit (servocontrolled skin temperature derivative system) has been designed to control the thermal environment in closed incubators. This type of control acts to attain and closely maintain a thermal equilibrium between a neonate's skin temperature and the environment. The present study aims to discover if thermal equilibrium is located within a thermoneutral range defined from oxygen consumption VO2 and body temperature, and whether it is more appropriate to define an optimal thermal environment. As regards VO2 and body temperature, results show that the air temperature reached at thermal equilibrium fulfils the definition of thermoneutrality. According to these criteria, a small decrease (1:5 degrees C) from thermal equilibrium also provides a near thermoneutral environment to the neonate but induces sleep disturbances and an increase in body movements. These two additional parameters delineate a narrower thermoneutral zone than does minimal metabolic rate because VO2 can stay constant even when air and body temperatures decrease. The results suggest that thermal equilibrium might be assimilated with a thermal comfort zone. PMID:9374057
Choi, Jeunghwan; Bischof, John C
2010-02-01
It is well accepted in cryobiology that the temperature history and cooling rates experienced in biomaterials during freezing procedures correlate strongly with biological outcome. Therefore, heat transfer measurement and prediction in the cryogenic regime is central to the field. Although direct measurement of temperature history (i.e. heat transfer) can be performed, accuracy is usually achieved only for local measurements within a given system and cannot be readily generalized to another system without the aid of predictive models. The accuracy of these models rely upon thermal properties which are known to be highly dependent on temperature, and in the case of significant cryoprotectant loading, also on crystallized fraction. In this work, we review the available thermal properties of biomaterials in the cryogenic regime. The review shows a lack of properties for many biomaterials in the subzero temperature domain, and especially for systems with cryoprotective agents. Unfortunately, use of values from the limited data available (usually only down to -40 degrees C) lead to an underestimation of thermal property change (i.e. conductivity rise and specific heat drop due to ice crystallization) with lower temperatures. Conversely, use of surrogate values based solely on ice thermal properties lead to an overestimation of thermal property change for most biomaterials. Additionally, recent work extending the range of available thermal properties to -150 degrees C has shown that the thermal conductivity will drop in both PBS and tissue (liver) due to amorphous/glassy phases (versus crystalline) of biomaterials with the addition of cryoprotective additives such as glycerol. Thus, we investigated the implications of using approximated or constant property values versus measured temperature-dependent values for predicting temperature history during freezing in PBS (phosphate-buffered saline) and porcine liver with and without cryoprotectants (glycerol). Using measured
Geometrically thin, hot accretion disks - Topology of the thermal equilibrium curves
NASA Technical Reports Server (NTRS)
Kusunose, Masaaki; Mineshige, Shin
1992-01-01
All the possible thermal equilibrium states of geometrically thin alpha-disks around stellar-mass black holes are presented. A (vertically) one-zone disk model is employed and it is assumed that a main energy source is viscous heating of protons and that cooling is due to bremsstrahlung and Compton scattering. There exist various branches of the thermal equilibrium solution, depending on whether disks are effectively optically thick or thin, radiation pressure-dominated or gas pressure-dominated, composed of one-temperature plasmas or of two-temperature plasmas, and with high concentration of e(+)e(-) pairs or without pairs. The thermal equilibrium curves at high temperatures (greater than or approximately equal to 10 exp 8 K) are substantially modified by the presence of e(+)e(-) pairs. The thermal stability of these branches are examined.
Transition from thermal to turbulent equilibrium with a resulting electromagnetic spectrum
Ziebell, L. F.; Yoon, P. H.; Gaelzer, R.; Pavan, J.
2014-01-15
A recent paper [Ziebell et al., Phys. Plasmas 21, 010701 (2014)] discusses a new type of radiation emission process for plasmas in a state of quasi-equilibrium between the particles and enhanced Langmuir turbulence. Such a system may be an example of the so-called “turbulent quasi-equilibrium.” In the present paper, it is shown on the basis of electromagnetic weak turbulence theory that an initial thermal equilibrium state (i.e., only electrostatic fluctuations and Maxwellian particle distributions) transitions toward the turbulent quasi-equilibrium state with enhanced electromagnetic radiation spectrum, thus demonstrating that the turbulent quasi-equilibrium discussed in the above paper correctly describes the weakly turbulent plasma dynamically interacting with electromagnetic fluctuations, while maintaining a dynamical steady-state in the average sense.
NASA Astrophysics Data System (ADS)
Masnoon, Ahmed Shafkat; Bipasha, Ferdaushi Alam; Morshed, A. K. M. M.
2016-07-01
The effect of nanoparticles decoration on the thermal conductivity of a nanowire is studied using Non Equilibrium Molecular Dynamics (NEMD) simulation. The simulation was conducted using simplified molecular model with Lennard-Jones potential. Argon-like solid was used as the material for both the nanowire and nanoparticles. Nanoparticles were placed on the surface of the nanowire and also embedded inside the structure. Non-equilibrium molecular dynamics simulation was conducted by imposing temperature gradient along the length of the nanowire and thermal conductivity of the nanowire was calculated. Nanowire without any nanoparticles was used as the baseline data. Due to presence of nanoparticles thermal conductivity of the nanowire was observed to decrease and up to 40% reduction in thermal conductivity was observed. With the increase in number of the nanoparticles, thermal conductivity was observed to decrease; however size of nanoparticles has little effect.
On return to thermal equilibrium for the excess charge distribution in semiconductors
NASA Astrophysics Data System (ADS)
Paranjape, V. V.
1985-04-01
The relaxation time for the return to thermal equilibrium for the excess charge distribution in metals and in semiconductors is shown to be longer than the relaxation time derived in many textbooks. In semiconductors the relaxation of charge is accompanied by an increase in temperature of the charged carriers. The time of decay τT for the temperature is considerably longer than the time of decay for the excess charge. Hence the overall relaxation time for attaining thermal equilibrium is determined by τT.
The effects of thermal equilibrium and contrast in LWIR polarimetric images.
Tyo, J Scott; Ratliff, Bradley M; Boger, James K; Black, Wiley T; Bowers, David L; Fetrow, Matthew P
2007-11-12
Long-wave infrared (LWIR) polarimetric signatures provide the potential for day-night detection and identification of objects in remotely sensed imagery. The source of optical energy in the LWIR is usually due to thermal emission from the object in question, which makes the signature dependent primarily on the target and not on the external environment. In this paper we explore the impact of thermal equilibrium and the temperature of (unseen) background objects on LWIR polarimetric signatures. We demonstrate that an object can completely lose its polarization signature when it is in thermal equilibrium with its optical background, even if it has thermal contrast with the objects that appear behind it in the image. PMID:19550799
Influence of temperature on the single-stage ATAD process predicted by a thermal equilibrium model.
Cheng, Jiehong; Zhu, Jun; Kong, Feng; Zhang, Chunyong
2015-06-01
Autothermal thermophilic aerobic digestion (ATAD) is a promising biological process that will produce an effluent satisfying the Class A requirements on pathogen control and land application. The thermophilic temperature in an ATAD reactor is one of the critical factors that can affect the satisfactory operation of the ATAD process. This paper established a thermal equilibrium model to predict the effect of variables on the auto-rising temperature in an ATAD system. The reactors with volumes smaller than 10 m(3) could not achieve temperatures higher than 45 °C under ambient temperature of -5 °C. The results showed that for small reactors, the reactor volume played a key role in promoting auto-rising temperature in the winter. Thermophilic temperature achieved in small ATAD reactors did not entirely depend on the heat release from biological activities during degrading organic matters in sludges, but was related to the ambient temperature. The ratios of surface area-to-effective volume less than 2.0 had less impact on the auto-rising temperature of an ATAD reactor. The influence of ambient temperature on the auto-rising reactor temperature decreased with increasing reactor volumes. High oxygen transfer efficiency had a significant influence on the internal temperature rise in an ATAD system, indicating that improving the oxygen transfer efficiency of aeration devices was a key factor to achieve a higher removal rate of volatile solids (VS) during the ATAD process operation. Compared with aeration using cold air, hot air demonstrated a significant effect on maintaining the internal temperature (usually 4-5 °C higher). PMID:25881085
NASA Astrophysics Data System (ADS)
Zhou, Wenting; Yu, Hongwei
2015-05-01
We demonstrate that the Casimir-Polder force for a molecule near the surface of a real dielectric substrate out of thermal equilibrium displays distinctive behaviors as compared to that at thermal equilibrium. In particular, when the molecule-substrate separation is much less than the molecular transition wavelength, the CP force in the high-temperature limit can be dramatically manipulated by varying the relative magnitude of the temperatures of the substrate and the environment so that the attractive-to-repulsive transition can occur beyond a certain threshold temperature of either the substrate or the environment depending on which one is higher for molecules both in the ground and excited states. More remarkably, when the separation is comparable to the wavelength, such transitions which are impossible at thermal equilibrium may happen for longitudinally polarizable molecules with a small permittivity, while for isotropically polarizable ones the transitions can even occur at room temperature for some dielectric substrates such as sapphire and graphite which is much lower than the temperature for the transition to take place in the thermal equilibrium case, thus making the experimental demonstration of such force transitions easier.
Thermal Equilibrium of a Macroscopic Quantum System in a Pure State
NASA Astrophysics Data System (ADS)
Goldstein, Sheldon; Huse, David A.; Lebowitz, Joel L.; Tumulka, Roderich
2015-09-01
We consider the notion of thermal equilibrium for an individual closed macroscopic quantum system in a pure state, i.e., described by a wave function. The macroscopic properties in thermal equilibrium of such a system, determined by its wave function, must be the same as those obtained from thermodynamics, e.g., spatial uniformity of temperature and chemical potential. When this is true we say that the system is in macroscopic thermal equilibrium (MATE). Such a system may, however, not be in microscopic thermal equilibrium (MITE). The latter requires that the reduced density matrices of small subsystems be close to those obtained from the microcanonical, equivalently the canonical, ensemble for the whole system. The distinction between MITE and MATE is particularly relevant for systems with many-body localization for which the energy eigenfuctions fail to be in MITE while necessarily most of them, but not all, are in MATE. We note, however, that for generic macroscopic systems, including those with MBL, most wave functions in an energy shell are in both MATE and MITE. For a classical macroscopic system, MATE holds for most phase points on the energy surface, but MITE fails to hold for any phase point.
Convex Decompositions of Thermal Equilibrium for Non-interacting Non-relativistic Particles
NASA Astrophysics Data System (ADS)
Chenu, Aurelia; Branczyk, Agata; Sipe, John
2016-05-01
We provide convex decompositions of thermal equilibrium for non-interacting non-relativistic particles in terms of localized wave packets. These quantum representations offer a new tool and provide insights that can help relate to the classical picture. Considering that thermal states are ubiquitous in a wide diversity of fields, studying different convex decompositions of the canonical ensemble is an interesting problem by itself. The usual classical and quantum pictures of thermal equilibrium of N non-interacting, non-relativistic particles in a box of volume V are quite different. The picture in classical statistical mechanics is about (localized) particles with a range of positions and velocities; in quantum statistical mechanics, one considers the particles (bosons or fermions) associated with energy eigenstates that are delocalized through the whole box. Here we provide a representation of thermal equilibrium in quantum statistical mechanics involving wave packets with a localized coordinate representation and an expectation value of velocity. In addition to derive a formalism that may help simplify particular calculations, our results can be expected to provide insights into the transition from quantum to classical features of the fully quantum thermal state.
NUMERICAL SOLUTION FOR THE POTENTIAL AND DENSITY PROFILE OF A THERMAL EQUILIBRIUM SHEET BEAM
Bazouin, Steven M. Lund, Guillaume; Bazouin, Guillaume
2011-04-01
In a recent paper, S. M. Lund, A. Friedman, and G. Bazouin, Sheet beam model for intense space-charge: with application to Debye screening and the distribution of particle oscillation frequencies in a thermal equilibrium beam, in press, Phys. Rev. Special Topics - Accel. and Beams (2011), a 1D sheet beam model was extensively analyzed. In this complementary paper, we present details of a numerical procedure developed to construct the self-consistent electrostatic potential and density profile of a thermal equilibrium sheet beam distribution. This procedure effectively circumvents pathologies which can prevent use of standard numerical integration techniques when space-charge intensity is high. The procedure employs transformations and is straightforward to implement with standard numerical methods and produces accurate solutions which can be applied to thermal equilibria with arbitrarily strong space-charge intensity up to the applied focusing limit.
NUMERICAL SOLUTION FOR THE POTENTIAL AND DENSITY PROFILE OF A THERMAL EQUILIBRIUM SHEET BEAM
Lund, S M; Bazouin, G
2011-03-29
In a recent paper, S. M. Lund, A. Friedman, and G. Bazouin, Sheet beam model for intense space-charge: with application to Debye screening and the distribution of particle oscillation frequencies in a thermal equilibrium beam, in press, Phys. Rev. Special Topics - Accel. and Beams (2011), a 1D sheet beam model was extensively analyzed. In this complementary paper, we present details of a numerical procedure developed to construct the self-consistent electrostatic potential and density profile of a thermal equilibrium sheet beam distribution. This procedure effectively circumvents pathologies which can prevent use of standard numerical integration techniques when space-charge intensity is high. The procedure employs transformations and is straightforward to implement with standard numerical methods and produces accurate solutions which can be applied to thermal equilibria with arbitrarily strong space-charge intensity up to the applied focusing limit.
Steady State Transportation Cooling in Porous Media Under Local, Non-Thermal Equilibrium Fluid Flow
NASA Technical Reports Server (NTRS)
Rodriquez, Alvaro Che
2002-01-01
An analytical solution to the steady-state fluid temperature for 1-D (one dimensional) transpiration cooling has been derived. Transpiration cooling has potential use in the aerospace industry for protection against high heating environments for re-entry vehicles. Literature for analytical treatments of transpiration cooling has been largely confined to the assumption of thermal equilibrium between the porous matrix and fluid. In the present analysis, the fundamental fluid and matrix equations are coupled through a volumetric heat transfer coefficient and investigated in non-thermal equilibrium. The effects of varying the thermal conductivity of the solid matrix and the heat transfer coefficient are investigated. The results are also compared to existing experimental data.
Lunghi, Enrico; Manenti, Raoul; Canciani, Giancarlo; Scarì, Giorgio; Pennati, Roberta; Ficetola, Gentile Francesco
2016-08-01
Information on species thermal physiology is extremely important to understand species responses to environmental heterogeneity and changes. Thermography is an emerging technology that allows high resolution and accurate measurement of body temperature, but until now it has not been used to study thermal physiology of amphibians in the wild. Hydromantes terrestrial salamanders are strongly depending on ambient temperature for their activity and gas exchanges, but information on their body temperature is extremely limited. In this study we tested if Hydromantes salamanders are thermoconform, we assessed whether there are temperature differences among body regions, and evaluated the time required to reach the thermal equilibrium. During summers of 2014 and 2015 we analysed 56 salamanders (Hydromantes ambrosii and Hydromantes italicus) using infrared thermocamera. We photographed salamanders at the moment in which we found them and 1, 2, 3, 4, 5 and 15min after having kept them in the hands. Body temperature was equal to air temperature; salamanders attained the equilibrium with air temperature in about 8min, the time required to reach equilibrium was longer in individuals with large body size. We detected small temperature differences between body parts, the head being slightly warmer than the body and the tail (mean difference: 0.05°C). These salamanders quickly reach the equilibrium with the environment, thus microhabitat measurement allows obtaining accurate information on their tolerance limits. PMID:27503719
New Asymptotic Behavior of the Surface-Atom Force out of Thermal Equilibrium
Antezza, Mauro; Pitaevskii, Lev P.; Stringari, Sandro
2005-09-09
The Casimir-Polder-Lifshitz force felt by an atom near the surface of a substrate is calculated out of thermal equilibrium in terms of the dielectric function of the material and of the atomic polarizability. The new force decays like 1/z{sup 3} at large distances (i.e., slower than at equilibrium), exhibits a sizable temperature dependence, and is attractive or repulsive depending on whether the temperature of the substrate is higher or smaller than the one of the environment. Our predictions can be relevant for experiments with ultracold atomic gases. Both dielectric and metal substrates are considered.
Achieving Chemical Equilibrium: The Role of Imposed Conditions in the Ammonia Formation Reaction
ERIC Educational Resources Information Center
Tellinghuisen, Joel
2006-01-01
Under conditions of constant temperature T and pressure P, chemical equilibrium occurs in a closed system (fixed mass) when the Gibbs free energy G of the reaction mixture is minimized. However, when chemical reactions occur under other conditions, other thermodynamic functions are minimized or maximized. For processes at constant T and volume V,…
Strange scaling and relaxation of finite-size fluctuation in thermal equilibrium
NASA Astrophysics Data System (ADS)
Yamaguchi, Yoshiyuki Y.
2016-07-01
We numerically exhibit two strange phenomena of finite-size fluctuation in thermal equilibrium of a paradigmatic long-range interacting system having a second-order phase transition. One is a nonclassical finite-size scaling at the critical point, which differs from the prediction by statistical mechanics. With the aid of this strange scaling, the scaling theory for infinite-range models conjectures the nonclassical values of critical exponents for the correlation length. The other is relaxation of the fluctuation strength from one level to another in spite of being in thermal equilibrium. A scenario is proposed to explain these phenomena from the viewpoint of the Casimir invariants and their nonexactness in finite-size systems, where the Casimir invariants are conserved in the Vlasov dynamics describing the long-range interacting systems in the limit of large population. This scenario suggests appearance of the reported phenomena in a wide class of isolated long-range interacting systems.
Casimir-lifshitz force out of thermal equilibrium and asymptotic nonadditivity.
Antezza, Mauro; Pitaevskii, Lev P; Stringari, Sandro; Svetovoy, Vitaly B
2006-12-01
We investigate the force acting between two parallel plates held at different temperatures. The force reproduces, as limiting cases, the well-known Casimir-Lifshitz surface-surface force at thermal equilibrium and the surface-atom force out of thermal equilibrium recently derived by M. Antezza et al., Phys. Rev. Lett. 95, 113202 (2005)10.1103/PhysRevLett.95.113202. The asymptotic behavior of the force at large distances is explicitly discussed. In particular when one of the two bodies is a rarefied gas the force is not additive, being proportional to the square root of the density. Nontrivial crossover regions at large distances are also identified. PMID:17155801
Heating of thermal non-equilibrium ions by Alfvén wave via nonresonant interaction
NASA Astrophysics Data System (ADS)
Liu, Hai-Feng; Wang, Shi-Qing; Li, Ke-Hua
2013-10-01
Pickup of thermal non-equilibrium ions by Alfvén wave via nonresonant wave-particle interaction is investigated by means of analytical test-particle theory. Some interesting and new results are found. No matter what the initial velocity distribution is, if the background magnetic field, the Alfvén speed, and the Alfvén magnetic field are fixed, the average parallel velocity never changes when t →∞. Heating effects in the perpendicular and parallel direction just depend on the initial temperature, and the perpendicular temperature increase is more prominent. It is noted that the heating effect of thermal non-equilibrium ions (Kappa ions) is weaker than that of the Maxwellian. This phenomenon may be relative to the heating of ions in the solar corona as well as in some toroidal confinement fusion devices.
Strange scaling and relaxation of finite-size fluctuation in thermal equilibrium.
Yamaguchi, Yoshiyuki Y
2016-07-01
We numerically exhibit two strange phenomena of finite-size fluctuation in thermal equilibrium of a paradigmatic long-range interacting system having a second-order phase transition. One is a nonclassical finite-size scaling at the critical point, which differs from the prediction by statistical mechanics. With the aid of this strange scaling, the scaling theory for infinite-range models conjectures the nonclassical values of critical exponents for the correlation length. The other is relaxation of the fluctuation strength from one level to another in spite of being in thermal equilibrium. A scenario is proposed to explain these phenomena from the viewpoint of the Casimir invariants and their nonexactness in finite-size systems, where the Casimir invariants are conserved in the Vlasov dynamics describing the long-range interacting systems in the limit of large population. This scenario suggests appearance of the reported phenomena in a wide class of isolated long-range interacting systems. PMID:27575102
Sharma, Rohit; Singh, Kuldip
2014-03-15
In the present work, two cases of thermal plasma have been considered; the ground state plasma in which all the atoms and ions are assumed to be in the ground state and the excited state plasma in which atoms and ions are distributed over various possible excited states. The variation of Zγ, frozen isentropic coefficient and the isentropic coefficient with degree of ionization and non-equilibrium parameter θ(= T{sub e}/T{sub h}) has been investigated for the ground and excited state helium and argon plasmas at pressures 1 atm, 10 atm, and 100 atm in the temperature range from 6000 K to 60 000 K. For a given value of non-equilibrium parameter, the relationship of Zγ with degree of ionization does not show any dependence on electronically excited states in helium plasma whereas in case of argon plasma this dependence is not appreciable till degree of ionization approaches 2. The minima of frozen isentropic coefficient shifts toward lower temperature with increase of non-equilibrium parameter for both the helium and argon plasmas. The lowering of non-equilibrium parameter decreases the frozen isentropic coefficient more emphatically in helium plasma at high pressures in comparison to argon plasma. The increase of pressure slightly reduces the ionization range over which isentropic coefficient almost remains constant and it does not affect appreciably the dependence of isentropic coefficient on non-equilibrium parameter.
Thermal boundary resistance in Si/Ge interfaces determined by approach-to-equilibrium simulations
NASA Astrophysics Data System (ADS)
Puligheddu, Marcello; Hahn, Konstanze; Melis, Claudio; Colombo, Luciano
2015-03-01
Nanostructured materials hold great promises as efficient thermoelectrics. In such materials, the propagation of phonons is hindered by the internal interfaces (grain boundaries), leading to a reduced overall thermal conductivity and, therefore, to a larger figure of merit. Any further improvement in this field does, however, require a better fundamental understanding of the specific interface effects on thermal transport. In the present work we use approach-to-equilibrium molecular dynamics simulations (AEMD) to investigate the interfacial thermal resistance (ITR) of Si/Ge interfaces, occurring in very promising nanostructured SiGe alloys. We discuss how ITR depends on the thickness of the interface layer, as well as on its composition. Furthermore, the effect of the heat flux direction has been investigated at ambient temperature showing lower ITR for thermal transport from Si to Ge than vice versa. This feature is discussed in connection to possible rectification effects. Present address: The Institute for Molecular Engineering, University of Chicago.
Phonon thermal transport outside of local equilibrium in nanowires via molecular dynamics
Zhou Ya; Strachan, Alejandro
2013-03-28
We study thermal transport through Pt nanowires that bridge planar contacts as a function of wire length and vibrational frequency of the contacts. When phonons in the contacts have lower average frequencies than those in the wires thermal transport occurs under conditions away from local equilibrium with low-frequency phonons experiencing a higher thermal gradient than high-frequency ones. This results in a size-dependent increase in the effective thermal conductivity of the wire with decreasing vibrational frequencies of the contacts. The interfacial resistivity when heat flows from the wire to the contact is also size-dependent and has the same physical origin in the lack of full equilibration in short nanowires. We develop a model based on a 1D atomic chain that captures the salient physics of the MD results.
NASA Technical Reports Server (NTRS)
Haskins, Justin; Kinaci, Alper; Sevik, Cem; Cagin, Tahir
2012-01-01
It is widely known that graphene and many of its derivative nanostructures have exceedingly high reported thermal conductivities (up to 4000 W/mK at 300 K). Such attractive thermal properties beg the use of these structures in practical devices; however, to implement these materials while preserving transport quality, the influence of structure on thermal conductivity should be thoroughly understood. For graphene nanostructures, having average phonon mean free paths on the order of one micron, a primary concern is how size influences the potential for heat conduction. To investigate this, we employ a novel technique to evaluate the lattice thermal conductivity from the Green-Kubo relations and equilibrium molecular dynamics in systems where phonon-boundary scattering dominates heat flow. Specifically, the thermal conductivities of graphene nanoribbons and carbon nanotubes are calculated in sizes up to 3 microns, and the relative influence of boundary scattering on thermal transport is determined to be dominant at sizes less than 1 micron, after which the thermal transport largely depends on the quality of the nanostructure interface. The method is also extended to carbon nanostructures (fullerenes) where phonon confinement, as opposed to boundary scattering, dominates, and general trends related to the influence of curvature on thermal transport in these materials are discussed.
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
The influence of thermal pressure on equilibrium models of hypermassive neutron star merger remnants
Kaplan, J. D.; Ott, C. D.; Roberts, L.; O'Connor, E. P.; Kiuchi, K.; Duez, M.
2014-07-20
The merger of two neutron stars leaves behind a rapidly spinning hypermassive object whose survival is believed to depend on the maximum mass supported by the nuclear equation of state (EOS), angular momentum redistribution by (magneto-)rotational instabilities, and spindown by gravitational waves. The high temperatures (∼5-40 MeV) prevailing in the merger remnant may provide thermal pressure support that could increase its maximum mass and, thus, its life on a neutrino-cooling timescale. We investigate the role of thermal pressure support in hypermassive merger remnants by computing sequences of spherically symmetric and axisymmetric uniformly and differentially rotating equilibrium solutions to the general-relativistic stellar structure equations. Using a set of finite-temperature nuclear EOS, we find that hot maximum-mass critically spinning configurations generally do not support larger baryonic masses than their cold counterparts. However, subcritically spinning configurations with mean density of less than a few times nuclear saturation density yield a significantly thermally enhanced mass. Even without decreasing the maximum mass, cooling and other forms of energy loss can drive the remnant to an unstable state. We infer secular instability by identifying approximate energy turning points in equilibrium sequences of constant baryonic mass parameterized by maximum density. Energy loss carries the remnant along the direction of decreasing gravitational mass and higher density until instability triggers collapse. Since configurations with more thermal pressure support are less compact and thus begin their evolution at a lower maximum density, they remain stable for longer periods after merger.
Non-Equilibrium Dynamics of an Atomic Gas Coupled to a Synthetic Thermal Body
NASA Astrophysics Data System (ADS)
Price, Craig; Liu, Qi; Zhao, Jianshi; Gemelke, Nathan
2016-05-01
One takes for Granted that thermal equilibrium can be established between two bodies by bringing them into physical contact with one another - viewed externally however, any statistical reservoir must therefore interact in ways such that the exchange of conserved quantities satisfy basic constraints which define the equilibrium it and any attached bodies reach. We describe the experimental construction of a ``synthetic thermal body,'' engineered by controlling the spatio-temporal modulation of nominally conservative optical, radio-frequency, and microwave couplings of a 87 Rb neutral atomic gas carrying hyperfine-spin to a spin-dependent spatially and temporally disordered bath. We measure the out-of-equilibrium response through its resultant diffusive motion, extracting drift and diffusion parameters, and making comparison to the Einstein-Smoluchowski and generalized fluctuation-dissipation relations. We discuss new limits on temperature and density for direct cooling by suitably engineered baths, by simultaneously avoiding the constraints of photon-recoil and density-dependent losses from light-assisted collisional processes in traditional laser cooling, and discuss new avenues in quantum simulation by coupling atomic gasses to statistically-generated and open environments.
Conversion of pine sawdust bio-oil (raw and thermally processed) over equilibrium FCC catalysts.
Bertero, Melisa; Sedran, Ulises
2013-05-01
A raw bio-oil from pine sawdust, the liquid product from its thermal conditioning and a synthetic bio-oil composed by eight model compounds representing the main chemical groups in bio-oils, were converted thermally and over a commercial equilibrium FCC catalyst. The experiments were performed in a fixed bed reactor at 500 °C. The highest hydrocarbon yield (53.5 wt.%) was obtained with the conditioned liquid. The coke yields were significant in all the cases, from 9 to 14 wt.%. The synthetic bio-oil produced lesser hydrocarbons and more oxygenated compounds and coke than the authentic feedstocks from biomass. The previous thermal treatment of the raw bio-oil had the positive effects of increasing 25% the yield of hydrocarbons, decreasing 55% the yield of oxygenated compounds and decreasing 20% the yield of coke, particularly the more condensed coke. PMID:23375765
Gheribi, Aïmen E; Salanne, Mathieu; Chartrand, Patrice
2015-03-28
The composition dependence of thermal transport properties of the (Na,K)Cl rocksalt solid solution is investigated through equilibrium molecular dynamics (EMD) simulations in the entire range of composition and the results are compared with experiments published in recent work [Gheribi et al., J. Chem. phys. 141, 104508 (2014)]. The thermal diffusivity of the (Na,K)Cl solid solution has been measured from 473 K to 823 K using the laser flash technique, and the thermal conductivity was deduced from critically assessed data of heat capacity and density. The thermal conductivity was also predicted at 900 K in the entire range of composition by a series of EMD simulations in both NPT and NVT statistical ensembles using the Green-Kubo theory. The aim of the present paper is to provide an objective analysis of the capability of EMD simulations in predicting the composition dependence of the thermal transport properties of halide solid solutions. According to the Klemens-Callaway [P. G. Klemens, Phys. Rev. 119, 507 (1960) and J. Callaway and H. C. von Bayer, Phys. Rev. 120, 1149 (1960)] theory, the thermal conductivity degradation of the solid solution is explained by mass and strain field fluctuations upon the phonon scattering cross section. A rigorous analysis of the consistency between the theoretical approach and the EMD simulations is discussed in detail. PMID:25833567
Gheribi, Aïmen E. Chartrand, Patrice; Salanne, Mathieu
2015-03-28
The composition dependence of thermal transport properties of the (Na,K)Cl rocksalt solid solution is investigated through equilibrium molecular dynamics (EMD) simulations in the entire range of composition and the results are compared with experiments published in recent work [Gheribi et al., J. Chem. phys. 141, 104508 (2014)]. The thermal diffusivity of the (Na,K)Cl solid solution has been measured from 473 K to 823 K using the laser flash technique, and the thermal conductivity was deduced from critically assessed data of heat capacity and density. The thermal conductivity was also predicted at 900 K in the entire range of composition by a series of EMD simulations in both NPT and NVT statistical ensembles using the Green-Kubo theory. The aim of the present paper is to provide an objective analysis of the capability of EMD simulations in predicting the composition dependence of the thermal transport properties of halide solid solutions. According to the Klemens-Callaway [P. G. Klemens, Phys. Rev. 119, 507 (1960) and J. Callaway and H. C. von Bayer, Phys. Rev. 120, 1149 (1960)] theory, the thermal conductivity degradation of the solid solution is explained by mass and strain field fluctuations upon the phonon scattering cross section. A rigorous analysis of the consistency between the theoretical approach and the EMD simulations is discussed in detail.
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.
Rosa, F. S. S.; Dalvit, D. A. R.; Milonni, P. W.
2010-03-15
The derivation of Casimir forces between dielectrics can be simplified by ignoring absorption, calculating energy changes due to displacements of the dielectrics, and only then admitting absorption by allowing permittivities to be complex. As a first step toward a better understanding of this situation we consider in this article the model of a dielectric as a collection of oscillators, each of which is coupled to a reservoir giving rise to damping and Langevin forces on the oscillators and a noise polarization acting as a source of a fluctuating electromagnetic field in the dielectric. The model leads naturally to expressions for the quantized electric and magnetic fields that are consistent with those obtained in approaches that diagonalize the coupled system of oscillators for the dielectric medium, the reservoir, and the electromagnetic field. It also results in a fluctuation-dissipation relation between the noise polarization and the imaginary part of the permittivity; comparison with the Rytov fluctuation-dissipation relation employed in the well-known Lifshitz theory for the van der Waals (or Casimir) force shows that the Lifshitz theory is actually a classical stochastic electrodynamical theory. The approximate classical expression for the energy density in a band of frequencies at which absorption in a dielectric is negligible is shown to be exact as a spectral thermal equilibrium expectation value in quantum electrodynamic theory. Our main result is the derivation of an expression for the QED energy density of a uniform dispersive, absorbing media in thermal equilibrium. The spectral density of the energy is found to have the same form with or without absorption. We also show how the fluctuation-dissipation theorem ensures a detailed balance of energy exchange between the (absorbing) medium, the reservoir, and the electromagnetic field in thermal equilibrium.
Thermal non-equilibrium analysis of porous annulus subjected to segmental isothermal heater - Part B
NASA Astrophysics Data System (ADS)
Al-Rashed, Abdullah A. A. A.; Salman, Ahmed N. J.; Khaleed, H. M. T.; Khan, T. M. Yunus; Kamangar, Sarfaraz
2016-06-01
Investigation of heat transfer in an annular porous cylinder subjected to segmental heating is carried out. Thermal non-equilibrium condition is applied to porous medium. Finite element method is used to solve the governing partial differential equations. The fluid is assumed to follow Darcy law. The boundary conditions are such that the fluid and solid phase have different temperatures at the hot wall. The current study is an extension of the paper part-A in this conference but elaborating the results for heat transfer behavior in terms of Nusselt number.
Gheribi, Aïmen E; Chartrand, Patrice
2016-02-28
A theoretical model for the description of thermal conductivity of molten salt mixtures as a function of composition and temperature is presented. The model is derived by considering the classical kinetic theory and requires, for its parametrization, only information on thermal conductivity of pure compounds. In this sense, the model is predictive. For most molten salt mixtures, no experimental data on thermal conductivity are available in the literature. This is a hindrance for many industrial applications (in particular for thermal energy storage technologies) as well as an obvious barrier for the validation of the theoretical model. To alleviate this lack of data, a series of equilibrium molecular dynamics (EMD) simulations has been performed on several molten chloride systems in order to determine their thermal conductivity in the entire range of composition at two different temperatures: 1200 K and 1300 K. The EMD simulations are first principles type, as the potentials used to describe the interactions have been parametrized on the basis of first principle electronic structure calculations. In addition to the molten chlorides system, the model predictions are also compared to a recent similar EMD study on molten fluorides and with the few reliable experimental data available in the literature. The accuracy of the proposed model is within the reported numerical and/or experimental errors. PMID:26931711
NASA Astrophysics Data System (ADS)
Zhou, Wenting; Yu, Hongwei
2014-09-01
We study the energy shift and the Casimir-Polder force of an atom out of thermal equilibrium near the surface of a dielectric substrate. We first generalize, adopting the local source hypothesis, the formalism proposed by Dalibard, Dupont-Roc, and Cohen-Tannoudji [J. Phys. (Paris) 43, 1617 (1982), 10.1051/jphys:0198200430110161700; J. Phys. (Paris) 45, 637 (1984), 10.1051/jphys:01984004504063700], which separates the contributions of thermal fluctuations and radiation reaction to the energy shift and allows a distinct treatment of atoms in the ground and excited states, to the case out of thermal equilibrium, and then we use the generalized formalism to calculate the energy shift and the Casimir-Polder force of an isotropically polarizable neutral atom. We identify the effects of the thermal fluctuations that originate from the substrate and the environment and discuss in detail how the Casimir-Polder force out of thermal equilibrium behaves in three different distance regions in both the low-temperature limit and the high-temperature limit for both the ground-state and excited-state atoms, with special attention devoted to the distinctive features as opposed to thermal equilibrium. In particular, we recover the distinctive behavior of the atom-wall force out of thermal equilibrium at large distances in the low-temperature limit recently found in a different theoretical framework, and furthermore we give a concrete region where this behavior holds.
Insight into lattice thermal impedance via equilibrium molecular dynamics: case study on Al
NASA Astrophysics Data System (ADS)
Evteev, Alexander V.; Levchenko, Elena V.; Momenzadeh, Leila; Belova, Irina V.; Murch, Graeme E.
2016-02-01
Using results of equilibrium molecular dynamics simulation in conjunction with the Green-Kubo formalism, we present a general treatment of thermal impedance of a crystal lattice with a monatomic unit cell. The treatment is based on an analytical expression for the heat current autocorrelation function which reveals, in a monatomic lattice, an energy gap between the origin of the phonon states and the beginning of the energy spectrum of the so-called acoustic short-range phonon modes. Although, we consider here the f.c.c. Al model as a case example, the analytical expression is shown to be consistent for different models of elemental f.c.c. crystals over a wide temperature range. Furthermore, we predict a frequency 'window' where the thermal waves can be generated in a monatomic lattice by an external periodic temperature perturbation.
NASA Astrophysics Data System (ADS)
Cartoixà, Xavier; Dettori, Riccardo; Melis, Claudio; Colombo, Luciano; Rurali, Riccardo
2016-07-01
We study thermal transport in porous Si nanowires (SiNWs) by means of approach-to-equilibrium molecular dynamics simulations. We show that the presence of pores greatly reduces the thermal conductivity, κ, of the SiNWs as long mean free path phonons are suppressed. We address explicitly the dependence of κ on different features of the pore topology—such as the porosity and the pore diameter—and on the nanowire (NW) geometry—diameter and length. We use the results of the molecular dynamics calculations to tune an effective model, which is capable of capturing the dependence of κ on porosity and NW diameter. The model illustrates the failure of Matthiessen's rule to describe the coupling between boundary and pore scattering, which we account for by the inclusion of an additional empirical term.
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.
Identifying student resources in reasoning about entropy and the approach to thermal equilibrium
NASA Astrophysics Data System (ADS)
Loverude, Michael
2015-12-01
[This paper is part of the Focused Collection on Upper Division Physics Courses.] As part of an ongoing project to examine student learning in upper-division courses in thermal and statistical physics, we have examined student reasoning about entropy and the second law of thermodynamics. We have examined reasoning in terms of heat transfer, entropy maximization, and statistical treatments of multiplicity and probability. In this paper, we describe student responses in interviews focused on the approach of macroscopic systems to thermal equilibrium. Our data suggest that students do not use a single simple model of entropy, but rather use a variety of conceptual resources. Individual students frequently shifted between resources, in some cases leading to contradictory predictions. Among the resources that students employed were some that have been previously described in the literature, including inappropriate use of conservation. However, our results suggest that student use of resources connected to disorder are neither simple nor monolithic. For example, many students used a previously unreported association between the equilibrium state of a system and an increase in order, rather than disorder.
NASA Astrophysics Data System (ADS)
Gao, Tianfu; Chen, Jincan
Based on the general model of thermally-driven Brownian motors, an equivalent cycle system is established and the Onsager coefficients and efficiency at the maximum power output of the system are analytically calculated from non-equilibrium thermodynamics. It is found that the Onsager reciprocity relation holds and the Onsager coefficients are affected by the main irreversibilities existing in practical systems. Only when the heat leak and the kinetic energy change of the particle in the system are negligible, can the determinant of the Onsager matrix vanish. It is also found that in the frame of non-equilibrium thermodynamics, the power output and efficiency of an irreversible Brownian motor can be expressed to be the same form as those of an irreversible Carnot heat engine, so the results obtained here are of general significance. Moreover, these results are used to analyze the performance characteristics of a class of thermally-driven Brownian motors so that some important conclusions in literature may be directly derived from the present paper.
Length dependence of thermal conductivity by approach-to-equilibrium molecular dynamics
NASA Astrophysics Data System (ADS)
Zaoui, Hayat; Palla, Pier Luca; Cleri, Fabrizio; Lampin, Evelyne
2016-08-01
The length dependence of thermal conductivity over more than two orders of magnitude has been systematically studied for a range of materials, interatomic potentials, and temperatures using the atomistic approach-to-equilibrium molecular dynamics (AEMD) method. By comparing the values of conductivity obtained for a given supercell length and maximum phonon mean free path (MFP), we find that such values are strongly correlated, demonstrating that the AEMD calculation with a supercell of finite length actually probes the thermal conductivity corresponding to a maximum phonon MFP. As a consequence, the less pronounced length dependence usually observed for poorer thermal conductors, such as amorphous silica, is physically justified by their shorter average phonon MFP. Finally, we compare different analytical extrapolations of the conductivity to infinite length and demonstrate that the frequently used Matthiessen rule is not applicable in AEMD. An alternative extrapolation more suitable for transient-time, finite-supercell simulations is derived. This approximation scheme can also be used to classify the quality of different interatomic potential models with respect to their capability of predicting the experimental thermal conductivity.
Spurgeon, H A; duBell, W H; Stern, M D; Sollott, S J; Ziman, B D; Silverman, H S; Capogrossi, M C; Talo, A; Lakatta, E G
1992-01-01
1. Single isolated rat cardiac myocytes were loaded with either the pentapotassium salt form or the acetoxymethyl ester (AM) form of the calcium-sensitive fluorescent probe, Indo-1. The relationship of the Indo-1 fluorescence transient, an index of the change in cytosolic calcium [Ca2+]i concentration, to the simultaneously measured cell length during the electrically stimulated twitch originating from slack length at 23 degrees C was evaluated. It was demonstrated that even if the Ca2+ dissociation rate from Indo-1 was assumed to be as slow as 10 s-1, the descending limb ('relaxation phase') of the Indo-1 fluorescence transient induced by excitation under these conditions is in equilibrium with the [Ca2+]i transient. Additionally, the extent of Indo-1 loading employed did not substantially alter the twitch characteristics. 2. A unique relationship between the fluorescence transient and cell length was observed during relaxation of contractions that varied in amplitude. This was manifest as a common trajectory in the cell length vs. [Ca2+]i phase-plane diagrams beginning at the time of cell relengthening. The common trajectory could also be demonstrated in Indo-1 AM-loaded cells. The Indo-1 fluorescence-length relation defined by this common trajectory is steeper than that described by the relation of peak contraction amplitude and peak fluorescence during the twitch contractions. 3. The trajectory of the [Ca2+]i-length relation elicited via an abrupt, rapid, brief (200 ms) pulse of caffeine directly onto the cell surface or by 'tetanization' of cells in the presence of ryanodine is identical to the common [Ca2+]i-length trajectory formed by electrically stimulated contractions of different magnitudes. As the [Ca2+]i and length transients induced by caffeine application or during tetanization in the presence of ryanodine develop with a much slower time course than those elicited by electrical stimulation, the common trajectory is not fortuitous, i.e. it cannot be
NASA Technical Reports Server (NTRS)
Tuchman, Y.; Mineshige, S.; Wheeler, J. C.
1990-01-01
The thermal equilibrum structure and dynamical behavior of externally irradiated accretion disks are investigated. For radiative disks only the surface layer is heated, while for convective disks the heat penetrates deeply into the disk. For sufficiently strong radiation and given irradiation flux F(irr), the disk is completely stabilized against thermal instabilities of the sort invoked to explain dwarf novae. For moderately strong irradiation there is still an unstable branch in the thermal equilibrium curve. In typical soft X-ray transients, the disk is unstable against the dwarf-nova type instability. Fixed F(irr) on accretion disk annuli reduces the amplitude and the quiescent times and increases the outburst duration of the resultant light curves. Varying F(irr) in proportion to the mass accretion rate at the disks's inner edge results in light curves with a plateau in the decay from outbursts. In the case when irradiation is suddenly switched on, a temperature inversion results which leads to the formation of an accretion corona.
Ostriker, Eve C.; McKee, Christopher F.; Leroy, Adam K. E-mail: cmckee@astro.berkeley.ed
2010-10-01
We develop a model for the regulation of galactic star formation rates {Sigma}{sub SFR} in disk galaxies, in which interstellar medium (ISM) heating by stellar UV plays a key role. By requiring that thermal and (vertical) dynamical equilibrium are simultaneously satisfied within the diffuse gas, and that stars form at a rate proportional to the mass of the self-gravitating component, we obtain a prediction for {Sigma}{sub SFR} as a function of the total gaseous surface density {Sigma} and the midplane density of stars+dark matter {rho}{sub sd}. The physical basis of this relationship is that the thermal pressure in the diffuse ISM, which is proportional to the UV heating rate and therefore to {Sigma}{sub SFR}, must adjust until it matches the midplane pressure value set by the vertical gravitational field. Our model applies to regions where {Sigma} {approx}< 100 M{sub sun} pc{sup -2}. In low-{Sigma}{sub SFR} (outer-galaxy) regions where diffuse gas dominates, the theory predicts that {Sigma}{sub SFR{proportional_to}{Sigma}{radical}}({rho}{sub sd}). The decrease of thermal equilibrium pressure when {Sigma}{sub SFR} is low implies, consistent with observations, that star formation can extend (with declining efficiency) to large radii in galaxies, rather than having a sharp cutoff at a fixed value of {Sigma}. The main parameters entering our model are the ratio of thermal pressure to total pressure in the diffuse ISM, the fraction of diffuse gas that is in the warm phase, and the star formation timescale in self-gravitating clouds; all of these are (at least in principle) direct observables. At low surface density, our model depends on the ratio of the mean midplane FUV intensity (or thermal pressure in the diffuse gas) to the star formation rate, which we set based on solar-neighborhood values. We compare our results to recent observations, showing good agreement overall for azimuthally averaged data in a set of spiral galaxies. For the large flocculent spiral
Simulating ionic thermal trasport by equilibrium ab-initio molecular dynamics
NASA Astrophysics Data System (ADS)
Marcolongo, Aris; Umari, Paolo; Baroni, Stefano
2014-03-01
The Green-Kubo approach to thermal transport is often considered to be incompatible with ab-initio molecular dynamics (AIMD) because a suitable quantum-mechanical definition of the heat current is not readily available, due to the ill-definedness of the microscopic energy density to which it is related by the continuity equation. We argue that a similar difficulty actually exists in classical mechanics as well, and we address the conditions that have to be fulfilled in order for the physically well defined transport coefficients to be independent of the ill defined microscopic energy density from which they derive. We then provide two alternative approaches to calculating thermal conductivites from equilibrium AIMD. The first is based on the Green-Kubo formula, supplemented with an expression for the energy current, which is a generalization of Thouless' expression for the adiabatic charge current. The second approach, which avoids the recourse to an energy current altogether, rests on an efficient and accurate extrapolation to infinite wavelengths of the energy-density time correlation functions. The two methods are compared on a simple classical test bed, and their implementation in AIMD is demonstrated with the calculation of the thermal conductivity of simple fluids.
Thermal equilibrium in gas-discharge plasma of low pressure mercury lamp
NASA Astrophysics Data System (ADS)
Gorbunkov, V. I.; Solomonov, V. I.
2015-12-01
A study was conducted emission spectra germicidal low pressure mercury lamp at currents 100-306 mA located in a closed opaque cavity. It is shown that the lamps located in the cavity with perfectly reflecting and absorbing internal surfaces, in the emission resonance line of mercury is dominant at λr = 253.65 nm. The same pattern is observed in the tube placed in a cavity with diffusely reflecting surface at a low current of about 100 mA. However the picture of spectrum changes at higher discharge current. The spectrum of the lamp with arc discharge at a current of 306 mA contains the maxima of the spectral lines. Its intensities are approximately described by Planck's radiation law at the temperature of 9270 +/- 230 K. The mechanisms of establish thermal equilibrium are discussed.
Microscopic theory of the Casimir force at thermal equilibrium: large-separation asymptotics.
Buenzli, P R; Martin, Ph A
2008-01-01
We present an entirely microscopic calculation of the Casimir force f(d) between two metallic plates in the limit of large separation d . The models of metals consist of mobile quantum charges in thermal equilibrium with the photon field at positive temperature T . Fluctuations of all degrees of freedom, matter and field, are treated according to the principles of quantum electrodynamics and statistical physics without recourse to approximations or intermediate assumptions. Our main result is the correctness of the asymptotic universal formula f(d) approximately -zeta(3)kBT/8pid3, d-->infinity. This supports the fact that, in the framework of the Lifshitz theory of electromagnetic fluctuations, transverse electric modes do not contribute in this regime. Moreover, the microscopic origin of universality is seen to rely on perfect screening sum rules that hold in great generality for conducting media. PMID:18351825
Thermal non-equilibrium analysis of porous annulus subjected to segmental isothermal heater - Part A
NASA Astrophysics Data System (ADS)
Al-Rashed, Abdullah A. A. A.; Salman, Ahmed N. J.; Khaleed, H. M. T.; Khan, T. M. Yunus; Kamangar, Sarfaraz
2016-06-01
The objective of present study is to evaluate the effect of the length and location of segmental heating of inner radius of annular cylinder containing porous medium between inner and outer radii. The fluid and solid matrix of porous medium are assumed to have temperature discrepancy subjected to isothermal heating of heater. The fluid is assumed to follow Darcy law and two separate equations are considered for energy transport to account for the thermal non-equilibrium condition. The boundary conditions are such that fluid and solid phase have different temperatures at the hot wall. The study is conducted for different lengths of heater corresponding to the 20%, 35% and 50% of the total height of the cylinder. The location of the heater is varied to three positions i.e. bottom section, mid-section and top of the cylinder.
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.
Nonlocal-thermal-equilibrium model of a pulsed capillary discharge waveguide.
Broks, B H P; Garloff, K; van der Mullen, J J A M
2005-01-01
Slow pulsed capillary discharges are under investigation for use as plasma channel waveguides in laser-wakefield acceleration. In this study, we present a non-local thermal equilibrium (non-LTE) plasma model with a model for the wall temperature coupled to it. This model is used to describe an example of a slow pulsed capillary discharge, and the results are compared with experimental results. The agreement is satisfactory, indicating suitability of our model. Significant deviations from LTE are found during the formation of the plasma channel. The model is also used to study the influence of the discharge current on the guiding properties. It was found that this influence is small over most of the current range that was investigated. PMID:15697729
Effect of thermal pretreatment on equilibrium moisture content of lignocellulosic biomass.
Acharjee, Tapas C; Coronella, Charles J; Vasquez, Victor R
2011-04-01
The equilibrium moisture content (EMC) of raw lignocellulosic biomass, along with four samples subjected to thermal pretreatment, was measured at relative humidities ranging from 11% to 97% at a constant temperature of 30 °C. Three samples were prepared by treatment in hot compressed water by a process known as wet torrefaction, at temperatures of 200, 230, and 260 °C. An additional sample was prepared by dry torrefaction at 300 °C. Pretreated biomass shows EMC below that of raw biomass. This indicates that pretreated biomass, both dry and wet torrefied, is more hydrophobic than raw biomass. The EMC results were correlated with a recent model that takes into account additional non-adsorption interactions of water, such as mixing and swelling. The model offers physical insight into the water activity in lignocellulosic biomass. PMID:21310606
Thermal equilibrium of non-neutral plasma in dipole magnetic field
Sato, N.; Kasaoka, N.; Yoshida, Z.
2015-04-15
Self-organization of a long-lived structure is one of the remarkable characteristics of macroscopic systems governed by long-range interactions. In a homogeneous magnetic field, a non-neutral plasma creates a “thermal equilibrium,” which is a Boltzmann distribution on a rigidly rotating frame. Here, we study how a non-neutral plasma self-organizes in inhomogeneous magnetic field; as a typical system, we consider a dipole magnetic field. In this generalized setting, the plasma exhibits its fundamental mechanism that determines the relaxed state. The scale hierarchy of adiabatic invariants is the determinant; the Boltzmann distribution under the topological constraint by the robust adiabatic invariants (hence, the homogeneous distribution with respect to the fragile invariant) is the relevant relaxed state, which turns out to be a rigidly rotating clump of particles (just same as in a homogeneous magnetic field), while the density is no longer homogeneous.
Complex time dependent wave packet technique for thermal equilibrium systems - Electronic spectra
NASA Technical Reports Server (NTRS)
Reimers, J. R.; Wilson, K. R.; Heller, E. J.
1983-01-01
A time dependent wave packet method is presented for the rapid calculation of the properties of systems in thermal equilibrium and is applied, as an illustration, to electronic spectra. The thawed Gaussian approximation to quantum wave packet dynamics combined with evaluation of the density matrix operator by imaginary time propagation is shown to give exact electronic spectra for harmonic potentials and excellent results for both a Morse potential and for the band contours of the three transitions of the visible electronic absorption spectrum of the iodine molecule. The method, in principle, can be extended to many atoms (e.g., condensed phases) and to other properties (e.g., infrared and Raman spectra and thermodynamic variables).
The Thermal Equilibrium Solution of a Generic Bipolar Quantum Hydrodynamic Model
NASA Astrophysics Data System (ADS)
Unterreiter, Andreas
The thermal equilibrium state of a bipolar, isothermic quantum fluid confined to a bounded domain ,d = 1,2 or d = 3 is entirely described by the particle densities n, p, minimizing the energy
Ueda, Keisuke; Higashi, Kenjirou; Yamamoto, Keiji; Moribe, Kunikazu
2015-04-01
The maintenance mechanism of the supersaturated state of poorly water-soluble drugs, glibenclamide (GLB) and chlorthalidone (CLT), in hydroxypropyl methylcellulose acetate succinate (HPMC-AS) solution was investigated at a molecular level. HPMC-AS suppressed drug crystallization from supersaturated drug solution and maintained high supersaturated level of drugs with small amount of HPMC-AS for 24 h. However, the dissolution of crystalline GLB into HPMC-AS solution failed to produce supersaturated concentrations, although supersaturated concentrations were achieved by adding amorphous GLB to HPMC-AS solution. HPMC-AS did not improve drug dissolution and/or solubility but efficiently inhibited drug crystallization from supersaturated drug solutions. Such an inhibiting effect led to the long-term maintenance of the amorphous state of GLB in HPMC-AS solution. NMR measurements showed that HPMC-AS suppressed the molecular mobility of CLT depending on their supersaturation level. Highly supersaturated CLT in HPMC-AS solution formed a gel-like structure with HPMC-AS in which the molecular mobility of the CLT was strongly suppressed. The gel-like structure of HPMC-AS could inhibit the reorganization from drug prenuclear aggregates to the crystal nuclei and delay the formation of drug crystals. The prolongation subsequently led to the redissolution of the aggregated drugs in aqueous solution and formed the equilibrium state at the supersaturated drug concentration in HPMC-AS solution. The equilibrium state formation of supersaturated drugs by HPMC-AS should be an essential mechanism underlying the marked drug concentration improvement. PMID:25723893
A numerical model of non-equilibrium thermal plasmas. I. Transport properties
Zhang XiaoNing; Xia WeiDong; Li HePing; Murphy, Anthony B.
2013-03-15
A self-consistent and complete numerical model for investigating the fundamental processes in a non-equilibrium thermal plasma system consists of the governing equations and the corresponding physical properties of the plasmas. In this paper, a new kinetic theory of the transport properties of two-temperature (2-T) plasmas, based on the solution of the Boltzmann equation using a modified Chapman-Enskog method, is presented. This work is motivated by the large discrepancies between the theories for the calculation of the transport properties of 2-T plasmas proposed by different authors in previous publications. In the present paper, the coupling between electrons and heavy species is taken into account, but reasonable simplifications are adopted, based on the physical fact that m{sub e}/m{sub h} Much-Less-Than 1, where m{sub e} and m{sub h} are, respectively, the masses of electrons and heavy species. A new set of formulas for the transport coefficients of 2-T plasmas is obtained. The new theory has important physical and practical advantages over previous approaches. In particular, the diffusion coefficients are complete and satisfy the mass conversation law due to the consideration of the coupling between electrons and heavy species. Moreover, this essential requirement is satisfied without increasing the complexity of the transport coefficient formulas. Expressions for the 2-T combined diffusion coefficients are obtained. The expressions for the transport coefficients can be reduced to the corresponding well-established expressions for plasmas in local thermodynamic equilibrium for the case in which the electron and heavy-species temperatures are equal.
Bian, Xin; Li, Zhen; Deng, Mingge; Karniadakis, George Em
2015-11-01
truncated side of the SDPD simulation. In the EBC buffer, the velocity of particles is drawn from a known Gaussian distribution, that is, the Maxwell-Boltzmann distribution. Due to the finite range of spatial correlation, the density of particles in the EBC buffer must be drawn from a conditional Gaussian distribution, which takes into account the available density distribution of neighboring interior particles. We introduce a Kriging method to provide such a conditional distribution and hence preserve the spatial correlation of density. Spatial and temporal correlations of SDPD simulations in the truncated domain are compared to that in a single complete domain. We find that a gap region between the buffer and interior is important to reduce the extra dissipation generated by the artificial buffer at equilibrium, rendering more investigations necessary for thermal fluctuations in the multiscale coupling of nonequilibrium flows. PMID:26651811
NASA Astrophysics Data System (ADS)
Bian, Xin; Li, Zhen; Deng, Mingge; Karniadakis, George Em
2015-11-01
truncated side of the SDPD simulation. In the EBC buffer, the velocity of particles is drawn from a known Gaussian distribution, that is, the Maxwell-Boltzmann distribution. Due to the finite range of spatial correlation, the density of particles in the EBC buffer must be drawn from a conditional Gaussian distribution, which takes into account the available density distribution of neighboring interior particles. We introduce a Kriging method to provide such a conditional distribution and hence preserve the spatial correlation of density. Spatial and temporal correlations of SDPD simulations in the truncated domain are compared to that in a single complete domain. We find that a gap region between the buffer and interior is important to reduce the extra dissipation generated by the artificial buffer at equilibrium, rendering more investigations necessary for thermal fluctuations in the multiscale coupling of nonequilibrium flows.
Thermal equilibrium properties of surface hopping with an implicit Langevin bath
Sherman, M. C.; Corcelli, S. A.
2015-01-14
The ability of fewest switches surface hopping (FSSH) approach, where the classical degrees of freedom are coupled to an implicit Langevin bath, to establish and maintain an appropriate thermal equilibrium was evaluated in the context of a three site model for electron transfer. The electron transfer model consisted of three coupled diabatic states that each depends harmonically on the collective bath coordinate. This results in three states with increasing energy in the adiabatic representation. The adiabatic populations and distributions of the collective solvent coordinate were monitored during the course of 250 ns FSSH-Langevin (FSSH-L) simulations performed at a broad range of temperatures and for three different nonadiabatic coupling strengths. The agreement between the FSSH-L simulations and numerically exact results for the adiabatic population ratios and solvent coordinate distributions was generally favorable. The FSSH-L method produces a correct Boltzmann distribution of the solvent coordinate on each of the adiabats, but the integrated populations are slightly incorrect because FSSH does not rigorously obey detailed balance. The overall agreement is better at high temperatures and for high nonadiabatic coupling, which agrees with a previously reported analytical and simulation analysis [J. R. Schmidt, P. V. Parandekar, and J. C. Tully, J. Chem. Phys. 129, 044104 (2008)] on a two-level system coupled to a classical bath.
Non-Thermal Equilibrium Atmospheric Pressure Glow-Like Discharge Plasma Jet
NASA Astrophysics Data System (ADS)
Chang, Zhengshi; Yao, Congwei; Zhang, Guanjun
2016-01-01
Non-thermal equilibrium atmospheric pressure plasma jet (APPJ) is a cold plasma source that promises various innovative applications, and the uniform APPJ is more favored. Glow discharge is one of the most effective methods to obtain the uniform discharge. Compared with the glow dielectric barrier discharge (DBD) in atmospheric pressure, pure helium APPJ shows partial characteristics of both the glow discharge and the streamer. In this paper, considering the influence of the Penning effect, the electrical and optical properties of He APPJ and Ar/NH3 APPJ were researched. A word “Glow-like APPJ” is used to characterize the uniformity of APPJ, and it was obtained that the basic characteristics of the glow-like APPJ are driven by the kHz AC high voltage. The results can provide a support for generating uniform APPJ, and lay a foundation for its applications. supported by National Natural Science Foundation of China (Nos. 51307133, 51125029, 51221005) and the Fundamental Research Funds for the Central Universities of China (Nos. xjj2012132, xkjc2013004)
NASA Astrophysics Data System (ADS)
Berezin, Y. A.; Trofimov, V. M.
1995-12-01
A critical review of hydrodynamical models with asymmetric stress tensor is given. Particular attention is focused on the balance law of angular momentum as the necessary element for a correct description of the internal motions of turbulent oriented eddies. On the basis of this analysis a non-equilibrium turbulence model is proposed that is shown to be close to the hydrodynamic equations with intrinsic rotation and helical turbulence. We employ this model in the study of the initial stage of thermal convection in a horizontal layer of a rotating non-equilibrium turbulent fluid that is heated from below. Linearizing the balance equations of mass, momentum, angular momentum and energy yields the boundary value problem, from which the general properties of the spectrum are determined. In the case of the horizontal layer with equilibrium boundary conditions on free boundaries we study the influence of the rotation and turbulent motion on the convective instability.
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.
Non-equilibrium simulations of thermally induced electric fields in water.
Wirnsberger, P; Fijan, D; Šarić, A; Neumann, M; Dellago, C; Frenkel, D
2016-06-14
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 × 10(7) and 5 × 10(7) 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. PMID:27305991
Shiraishi, Hiroyuki
2008-04-28
Numerical Analyses on Laser-Supported Plasma (LSP) have been performed for researching the mechanism of laser absorption occurring in the laser propulsion system. Above all, Laser-Supported Detonation (LSD), categorized as one type of LSP, is considered as one of the most important phenomena because it can generate high pressure and high temperature for performing highly effective propulsion. For simulating generation and propagation of LSD wave, I have performed thermal non-equilibrium analyses by Navier-stokes equations, using a CO{sub 2} gasdynamic laser into an inert gas, where the most important laser absorption mechanism for LSD propagation is Inverse Bremsstrahlung. As a numerical method, TVD scheme taken into account of real gas effects and thermal non-equilibrium effects by using a 2-temperature model, is applied. In this study, I analyze a LSD wave propagating through a conical nozzle, where an inner space of an actual laser propulsion system is simplified.
HOW DOES A SYSTEM RESPOND WHEN DRIVEN AWAY FROM THERMAL EQUILIBRIUM?
C. JARZYNSKI
2001-03-01
It is widely appreciated that our understanding of non-equilibrium phenomena has not kept pace with its equilibrium counterpart. In recent years, however, consideration of the above question, posed at the microscopic level of statistical mechanics, has yielded some intriguing theoretical results distinguished by two common features. First, they remain valid far from equilibrium, that is, even if the system is disturbed violently from its initial equilibrium state. Second, they incorporate information about the history of the system over some span of time: effectively, these are statistical predictions about what we would see if we could watch a movie of the system filmed at the atomic level, rather than predictions about individual snapshots. To date, this work has been theoretical, though supplemented with numerical simulations. However, in the current issue of PNAS, Hummer and Szabo [1] show how to combine these theoretical advances with single molecule manipulation experiments, so as to extract useful equilibrium information from non-equilibrium laboratory data. What these authors propose amounts to a novel method of deducing the equilibrium mechanical properties of individual molecules.
Zhang, Le; Luo, Feng; Xu, Ruina; Jiang, Peixue; Liu, Huihai
2014-12-31
The heat transfer and fluid transport of supercritical CO_{2} 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 volumetric 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.
Gross, A; Levine, R D
2006-11-30
A cold atomic cluster can be very rapidly heated and compressed by a hypersonic impact at a hard surface. The impact can be simulated by computing a classical trajectory for the motion of the atoms. By suddenly confining the hot and dense cluster within a rigid container, it is possible to monitor the time evolution of the force acting on the faces of the container. It is found that the pressure computed this way very rapidly decays to a time-independent value. After a somewhat longer time, this value reproduces the value for the pressure computed as the sum of the kinetic and internal pressures. This agreement is expected for a system in equilibrium. These observations support the conclusion that there is a fast relaxation to thermal equilibrium in these essentially hard-sphere systems. The deviation from equilibrium is primarily due to the propagation of shock waves within the cluster. The equilibrium pressure can reach up to the megabar range. PMID:17125378
NASA Technical Reports Server (NTRS)
Drew, J. E.
1989-01-01
Ab initio ionization and thermal equilibrium models are calculated for the winds of O stars using the results of steady state radiation-driven wind theory to determine the input parameters. Self-consistent methods are used for the roles of H, He, and the most abundant heavy elements in both the statistical and the thermal equilibrium. The model grid was chosen to encompass all O spectral subtypes and the full range of luminosity classes. Results of earlier modeling of O star winds by Klein and Castor (1978) are reproduced and used to motivate improvements in the treatment of the hydrogen equilibrium. The wind temperature profile is revealed to be sensitive to gross changes in the heavy element abundances, but insensitive to other factors considered such as the mass-loss rate and velocity law. The reduced wind temperatures obtained in observing the luminosity dependence of the Si IV lambda 1397 wind absorption profile are shown to eliminate any prospect of explaining the observed O VI lambda 1036 line profiles in terms of time-independent radiation-driven wind theory.
NASA Astrophysics Data System (ADS)
Alaghemandi, Mohammad; Müller-Plathe, Florian; Böhm, Michael C.
2011-11-01
The thermal conductivity of composites of carbon nanotubes and polyamide-6,6 has been investigated using reverse non-equilibrium molecular dynamics simulations in a full atomistic resolution. It is found, in line with experiments, that the composites have thermal conductivities, which are only moderately larger than that of pure polyamide. The composite conductivities are orders of magnitude less than what would be expected from naïve additivity arguments. This means that the intrinsic thermal conductivities of isolated nanotubes, which exceed the best-conducting metals, cannot be harnessed for heat transport, when the nanotubes are embedded in a polymer matrix. The main reason is the high interfacial thermal resistance between the nanotubes and the polymer, which was calculated in addition to the total composite thermal conductivity as well as that of the subsystem. It hinders heat to be transferred from the slow-conducting polymer into the fast-conducting nanotubes and back into the polymer. This interpretation is in line with the majority of recent simulation works. An alternative explanation, namely, the damping of the long-wavelength phonons in nanotubes by the polymer matrix is not supported by the present calculations. These modes provide most of the polymers heat conduction. An additional minor effect is caused by the anisotropic structure of the polymer phase induced by the nearby nanotube surfaces. The thermal conductivity of the polymer matrix increases slightly in the direction parallel to the nanotubes, whereas it decreases perpendicular to it.
NASA Astrophysics Data System (ADS)
Celli, Michele; Barletta, Antonio; Storesletten, Leiv
2014-04-01
The effects of lack of local thermal equilibrium between the solid phase and the fluid phase are taken into account for the convective stability analysis of a horizontal porous layer. The layer is bounded by a pair of plane parallel walls which are impermeable and such that the lower wall is subject to a uniform flux heating, while the upper wall is isothermal. The local thermal non-equilibrium is modelled through a two-temperature formulation of the energy exchange between the phases, resulting in a pair of local energy balance equations: one for each phase. Small-amplitude disturbances of the basic rest state are envisaged to test the stability. Then, the standard normal mode procedure is adopted to detect the onset conditions of convective rolls. Beyond the Darcy-Rayleigh number, playing the role of order parameter for the transition to instability, the relevant dimensionless parameters are the inter-phase heat transfer parameter and the thermal conductivity ratio. The disturbance governing equations, formulated as an eigenvalue problem, are solved numerically by a shooting method. Results are reported for the neutral stability curves and for the critical values for the onset of instability.
NASA Astrophysics Data System (ADS)
Binder, Moritz; Barthel, Thomas
We compare matrix product purifications and minimally entangled typical thermal states (METTS) for the simulation of equilibrium states and finite-temperature response functions of strongly correlated quantum many-body systems. For METTS, we highlight the interplay of statistical and DMRG truncation errors, discuss the use of self-averaging effects, and describe schemes for the computation of response functions. We assess the computation costs and accuracies of the two methods for critical and gapped spin chains and the Bose-Hubbard model. For the same computation cost, purifications yield more accurate results than METTS except for temperatures well below the system's energy gap.
NASA Astrophysics Data System (ADS)
Binder, Moritz; Barthel, Thomas
We compare matrix product purifications and minimally entangled typical thermal states (METTS) for the simulation of equilibrium states and finite-temperature response functions of strongly correlated quantum many-body systems. For METTS, we highlight the interplay of statistical and DMRG truncation errors, discuss the use of self-averaging effects, and describe schemes for the computation of response functions. We assess the computation costs and accuracies of the two methods for critical and gapped spin chains and the Bose-Hubbard model. For the same computation cost, purifications yield more accurate results than METTS except for temperatures well below the system's energy gap. (Phys. Rev. B 92, 125119 (2015)
NASA Technical Reports Server (NTRS)
Defacio, B.; Vannevel, Alan; Brander, O.
1993-01-01
A formulation is given for a collection of phonons (sound) in a fluid at a non-zero temperature which uses the simple harmonic oscillator twice; one to give a stochastic thermal 'noise' process and the other which generates a coherent Glauber state of phonons. Simple thermodynamic observables are calculated and the acoustic two point function, 'contrast' is presented. The role of 'coherence' in an equilibrium system is clarified by these results and the simple harmonic oscillator is a key structure in both the formulation and the calculations.
NASA Astrophysics Data System (ADS)
Bruno, D.; Colonna, G.; Laricchiuta, A.; Capitelli, M.
2012-12-01
Internal and reactive contributions to the thermal conductivity of a local thermodynamic equilibrium nitrogen plasma have been calculated using the Chapman-Enskog method. Low-lying (LL) electronically excited states (i.e., states with the same principal quantum number of the ground state) and high-lying (HL) ones (i.e., states with principal quantum number n > 2) have been considered. Several models have been developed, the most accurate being a model that treats the LL states as separate species while disregarding the presence of HL states, on account of their enormous transport cross sections.
Bruno, D.; Colonna, G.; Laricchiuta, A.; Capitelli, M.
2012-12-15
Internal and reactive contributions to the thermal conductivity of a local thermodynamic equilibrium nitrogen plasma have been calculated using the Chapman-Enskog method. Low-lying (LL) electronically excited states (i.e., states with the same principal quantum number of the ground state) and high-lying (HL) ones (i.e., states with principal quantum number n> 2) have been considered. Several models have been developed, the most accurate being a model that treats the LL states as separate species while disregarding the presence of HL states, on account of their enormous transport cross sections.
Collins, David
2010-05-15
A general framework for regarding oracle-assisted quantum algorithms as tools for discriminating among unitary transformations is described. This framework is applied to the Deutsch-Jozsa problem and all possible quantum algorithms which solve the problem with certainty using oracle unitaries in a particular form are derived. It is also used to show that any quantum algorithm that solves the Deutsch-Jozsa problem starting with a quantum system in a particular class of initial, thermal equilibrium-based states of the type encountered in solution-state NMR can only succeed with greater probability than a classical algorithm when the problem size n exceeds {approx}10{sup 5}.
Counting of fermions and spins in strongly correlated systems in and out of thermal equilibrium
Braungardt, Sibylle; Rodriguez, Mirta; Glauber, Roy J.; Lewenstein, Maciej
2011-01-15
Atom counting theory can be used to study the role of thermal noise in quantum phase transitions and to monitor the dynamics of a quantum system. We illustrate this for a strongly correlated fermionic system, which is equivalent to an anisotropic quantum XY chain in a transverse field and can be realized with cold fermionic atoms in an optical lattice. We analyze the counting statistics across the phase diagram in the presence of thermal fluctuations and during its thermalization when the system is coupled to a heat bath. At zero temperature, the quantum phase transition is reflected in the cumulants of the counting distribution. We find that the signatures of the crossover remain visible at low temperature and are obscured with increasing thermal fluctuations. We find that the same quantities may be used to scan the dynamics during the thermalization of the system.
Some properties of correlations of quantum lattice systems in thermal equilibrium
Fröhlich, Jürg; Ueltschi, Daniel
2015-05-15
Simple proofs of uniqueness of the thermodynamic limit of KMS states and of the decay of equilibrium correlations are presented for a large class of quantum lattice systems at high temperatures. New quantum correlation inequalities for general Heisenberg models are described. Finally, a simplified derivation of a general result on power-law decay of correlations in 2D quantum lattice systems with continuous symmetries is given, extending results of McBryan and Spencer for the 2D classical XY model.
Lund, Steven M.; Friedman, Alex; Bazouin, Guillaume
2011-01-10
A one-dimensional Vlasov-Poisson model for sheet beams is reviewed and extended to provide a simple framework for analysis of space-charge effects. Centroid and rms envelope equations including image charge effects are derived and reasonable parameter equivalences with commonly employed 2D transverse models of unbunched beams are established. This sheet beam model is then applied to analyze several problems of fundamental interest. A sheet beam thermal equilibrium distribution in a continuous focusing channel is constructed and shown to have analogous properties to two- d three-dimensional thermal equilibrium models in terms of the equilibrium structure and Deybe screening properties. The simpler formulation for sheet beams is exploited to explicitly calculate the distribution of particle oscillation frequencies within a thermal equilibrium beam. It is shown that as space-charge intensity increases, the frequency distribution becomes broad, suggesting that beams with strong space-charge can have improved stability.
NASA Astrophysics Data System (ADS)
Khatami, Ehsan; Rigol, Marcos; Relaño, Armando; García-García, Antonio M.
2012-05-01
We study spectral properties and the dynamics after a quench of one-dimensional spinless fermions with short-range interactions and long-range random hopping. We show that a sufficiently fast decay of the hopping term promotes localization effects at finite temperature, which prevents thermalization even if the classical motion is chaotic. For slower decays, we find that thermalization does occur. However, within this model, the latter regime falls in an unexpected universality class, namely, observables exhibit a power-law (as opposed to an exponential) approach to their thermal expectation values.
NASA Astrophysics Data System (ADS)
Arzhanov, M. M.; Demchenko, P. F.; Eliseev, A. V.; Mokhov, I. I.
2008-10-01
The IAP RAS CM (Institute of Atmospheric Physics, Russian Academy of Sciences, climate model) has been extended to include a comprehensive scheme of thermal and hydrologic soil processes. In equilibrium numerical experiments with specified preindustrial and current concentrations of atmospheric carbon dioxide, the coupled model successfully reproduces thermal characteristics of soil, including the temperature of its surface, and seasonal thawing and freezing characteristics. On the whole, the model also reproduces soil hydrology, including the winter snow water equivalent and river runoff from large watersheds. Evapotranspiration from the soil surface and soil moisture are simulated somewhat worse. The equilibrium response of the model to a doubling of atmospheric carbon dioxide shows a considerable warming of the soil surface, a reduction in the extent of permanently frozen soils, and the general growth of evaporation from continents. River runoff increases at high latitudes and decreases in the subtropics. The results are in qualitative agreement with observational data for the 20th century and with climate model simulations for the 21st century.
Thermal denaturing of proteins: Equilibrium and transient studies using nonlinear infrared probes
NASA Astrophysics Data System (ADS)
Chung, H. S.; Khalil, M.; Smith, A. W.; Ganim, Z.; Tokmakoff, A.
Thermal unfolding of β-sheets in ribonuclease A and ubiquitin is revealed by disappearance of cross peaks in 2D IR spectra. Transient unfolding probed with vibrational echoes following a temperature jump reveals nanosecond to millisecond dynamics.
NASA Astrophysics Data System (ADS)
Singh, Gurpreet; Sharma, Rohit; Singh, Kuldip
2015-09-01
Thermodynamic properties (compressibility coefficient Z γ , specific heat at constant volume c v , adiabatic coefficient γ a , isentropic coefficient γ i s e n , and sound speed c s ) of non-local thermodynamic equilibrium hydrogen thermal plasma have been investigated for different values of pressure and non-equilibrium parameter θ (=Te/Th) in the electron temperature range from 6000 K to 60 000 K. In order to estimate the influence of pressure derivative of partition function on thermodynamic properties, two cases have been considered: (a) in which pressure derivative of partition function is taken into account in the expressions and (b) without pressure derivative of partition function in their expressions. Here, the case (b) represents expressions already available in literature. It has been observed that the temperature from which pressure derivative of partition function starts influencing a given thermodynamic property increases with increase of pressure and non-equilibrium parameter θ. Thermodynamic property in the case (a) is always greater than its value in the case (b) for compressibility coefficient and specific heat at constant volume, whereas for adiabatic coefficient, isentropic coefficient, and sound speed, its value in the case (a) is always less than its value in the case (b). For a given value of θ, the relationship of compressibility coefficient with degree of ionization depends upon pressure in the case (a), whereas it is independent of pressure in the case (b). Relative deviation between the two cases shows that the influence of pressure derivative of partition function is significantly large and increases with the augmentation of pressure and θ for compressibility coefficient, specific heat at constant volume, and adiabatic coefficient, whereas for isentropic coefficient and sound speed, it is marginal even at high values of pressure and non-equilibrium parameter θ.
NASA Astrophysics Data System (ADS)
Kim, Chang-Goo; Kim, Woong-Tae; Ostriker, Eve C.
2011-12-01
We use vertically resolved numerical hydrodynamic simulations to study star formation and the interstellar medium (ISM) in galactic disks. We focus on outer-disk regions where diffuse H I dominates, with gas surface densities Σ = 3-20 M⊙ pc-2 and star-plus-dark matter volume densities ρsd = 0.003-0.5 M⊙ pc-3. Star formation occurs in very dense, self-gravitating clouds that form by mergers of smaller cold cloudlets. Turbulence, driven by momentum feedback from supernova events, destroys bound clouds and puffs up the disk vertically. Time-dependent radiative heating (FUV from recent star formation) offsets gas cooling. We use our simulations to test a new theory for self-regulated star formation. Consistent with this theory, the disks evolve to a state of vertical dynamical equilibrium and thermal equilibrium with both warm and cold phases. The range of star formation surface densities and midplane thermal pressures is ΣSFR ∼ 10-4 to 10-2 M⊙ kpc-2 yr-1 and P th/k B ∼ 102 to 104 cm-3 K. In agreement with observations, turbulent velocity dispersions are ~7 km s-1 and the ratio of the total (effective) to thermal pressure is Ptot/Pth ∼ 4-5, across this whole range (provided shielding is similar to the solar neighborhood). We show that ΣSFR is not well correlated with Σ alone, but rather with Σ ρsd1/2, because the vertical gravity from stars and dark matter dominates in outer disks. We also find that ΣSFR has a strong, nearly linear correlation with Ptot, which itself is within ~13% of the dynamical equilibrium estimate Ptot, DE. The quantitative relationships we find between &SigmaSFR and the turbulent and thermal pressures show that star formation is highly efficient for energy and momentum production, in contrast to the low efficiency of mass consumption. Star formation rates adjust until the ISM's energy and momentum losses are replenished by feedback within a dynamical time.
Identifying Student Resources in Reasoning about Entropy and the Approach to Thermal Equilibrium
ERIC Educational Resources Information Center
Loverude, Michael
2015-01-01
As part of an ongoing project to examine student learning in upper-division courses in thermal and statistical physics, we have examined student reasoning about entropy and the second law of thermodynamics. We have examined reasoning in terms of heat transfer, entropy maximization, and statistical treatments of multiplicity and probability. In…
NASA Technical Reports Server (NTRS)
Lanyi, Gabor E.
2003-01-01
This viewgraph presentation reviews the 1901 work in Planck's constant and blackbody radiation law and the 1916 Einstein rederivation of the blackbody radiation law. It also reviews Wien's law. It also presents equations that demonstrate the thermal balance between radiation and matter.
NASA Astrophysics Data System (ADS)
Wiegel, Frederik W.; Perelson, Alan S.
1982-12-01
When placed in suspension red blood cells adhere face-to-face and form long, cylindrical, and sometimes branched structures called rouleaux. We use methods developed in statistical mechanics to compute various statistical properties describing the size and shape of rouleaux in thermodynamic equilibrium. This leads to analytical expressions for (1) the average number of rouleaux consisting of n cells and having m branch points; (2) the average number of cells per rouleau; (3) the average number of branch points per rouleau; and (4) the number of rouleaux with n cells in a system containing a total of N cells. We also derive asymptotic formulas that simplify these analytic expressions, and present numerical comparisons of the exact and asymptotic results.
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.
Aguirre-Loredo, Rocío Yaneli; Rodríguez-Hernández, Adriana Inés; Morales-Sánchez, Eduardo; Gómez-Aldapa, Carlos Alberto; Velazquez, Gonzalo
2016-04-01
Water molecules modify the properties of biodegradable films obtained from hydrophilic materials. Most studies dealing with thermal, mechanical and barrier properties of hydrophilic films are carried out under one relative humidity (RH) condition. The objective of this work was to evaluate the effect of the moisture content on the thermal, mechanical and barrier properties of chitosan films under several RH conditions. Microclimates, obtained with saturated salt solutions were used for conditioning samples and the properties of the films were evaluated under each RH condition. Chitosan films absorbed up to 40% of moisture at the higher RH studied. The percentage of elongation and the water vapour permeability increased while tensile strength, Young's modulus and glass transition temperature decreased, when the moisture content increased. The results suggest that the water molecules plasticized the polymer matrix, changing the properties when the films were in contact with high RH environments. PMID:26593528
Achievement of a low-outgassing white paint system for spacecraft thermal control
NASA Technical Reports Server (NTRS)
Seidenberg, B.; Park, J. J.; Clatterbuck, C.
1972-01-01
Test results and data for achieving a low-outgassing polymer resin suitable for potting or a paint pigment are presented. The resin, prepared in 0.5-kg (1-lb) batches, is acceptable for spacecraft use; its weight loss is less than 0.5 percent, and the volatile condensable materials are less than 0.05 percent. The paint adheres to a primed fiber glass or aluminum substrate. Results of UV irradiation, electron and proton radiation, and thermal cycling are presented.
Modeling the hot-dense plasma of the solar interior in and out of thermal equilibrium
NASA Astrophysics Data System (ADS)
Lin, Hsiao-Hsuan
within any solar model code. In the present work we have carried the technique of the MHD-based OPAL emulator to the CEFF-based OPAL emulator and successfully accomplished this goal. At the same time, we went beyond the earlier work by adding more terms. In particular, the previous MHD-based OPAL emulator was restricted to the approximation of a hydrogen plasma; our work is extended to the more realistic H-He mixture. In a separate part of the present work, we have examined a non-equilibrium effect in the solar interior. The effect is located in the zone of the sharp transition between the differential rotation in the convection zone and the solid-sphere rotation in the radiation zone beneath it. This transition was discovered by helioseismology in the 1980s, and the transition zone is called the solar tachocline. The tachocline is subject to strong shear and in many theories of the solar dynamo it plays important role. Being inspired by the well-known Soret effect, which states the mass diffusion drive by a temperature gradient, we have examined if there could also be mass diffusion by a shear flow. If such an effect were to exist, it would have potential applications to the solar tachocline and dynamo. We have run a so-called reverse non-equilibrium molecular dynamics (RNEMD) simulation. As a test, we first confirmed the Soret effect by the simulation, then we tested for a shear- driven analogous effect. As a result, we did not see the shear-driven Soret effect in our simulation. We do observe the normal Soret effect due to the temperature gradient caused by the numerical scheme we used.
Guidotti, R.A.
1986-06-10
A method is disclosed for preparing lithiated, particulate FeS/sub 2/ useful as a catholyte material in a lithium thermal battery, whereby the latter's voltage regulation properties are improved. The method comprises admixing FeS/sub 2/ and an amount of a lithium-containing compound, whereby the resultant total composition falls in an invariant region of the metallurgical phase diagram of its constituent components. Said lithium-containing compound and FeS/sub 2/ are admixed together with a solid electrolyte compatible with said catholyte, and the mixture is heated at a temperature above the melting point of said electrolyte and at which said mixture reaches its thermodynamic equilibrium number of phases.
Guidotti, Ronald A.
1988-01-01
In a method for preparing lithiated, particulate FeS.sub.2 useful as a catholyte material in a lithium thermal battery, whereby the latter's voltage regulation properties are improved, comprising admixing FeS.sub.2 and an amount of a lithium-containing compound whereby the resultant total composition falls in an invariant region of the metallurgical phase diagram of its constituent components, an improvement comprises admixing said lithium-containing compound and FeS.sub.2 together with a solid electrolyte compatible with said catholyte, and heating the mixture at a temperature above the melting point of said electrolyte and at which said mixture reaches its thermodynamic equilibrium number of phases.
NASA Astrophysics Data System (ADS)
Chen, Jiliang; Jiang, Fangming
2016-02-01
With a previously developed numerical model, we perform a detailed study of the heat extraction process in enhanced or engineered geothermal system (EGS). This model takes the EGS subsurface heat reservoir as an equivalent porous medium while it considers local thermal non-equilibrium between the rock matrix and the fluid flowing in the fractured rock mass. The application of local thermal non-equilibrium model highlights the temperature-difference heat exchange process occurring in EGS reservoirs, enabling a better understanding of the involved heat extraction process. The simulation results unravel the mechanism of preferential flow or short-circuit flow forming in homogeneously fractured reservoirs of different permeability values. EGS performance, e.g. production temperature and lifetime, is found to be tightly related to the flow pattern in the reservoir. Thermal compensation from rocks surrounding the reservoir contributes little heat to the heat transmission fluid if the operation time of an EGS is shorter than 15 years. We find as well the local thermal equilibrium model generally overestimates EGS performance and for an EGS with better heat exchange conditions in the heat reservoir, the heat extraction process acts more like the local thermal equilibrium process.
Could a plasma in quasi-thermal equilibrium be associated to the "orphan" TeV flares?
NASA Astrophysics Data System (ADS)
Fraija, N.
2015-12-01
TeV γ-ray detections in flaring states without activity in X-rays from blazars have attracted much attention due to the irregularity of these "orphan" flares. Although the synchrotron self-Compton model has been very successful in explaining the spectral energy distribution and spectral variability of these sources, it has not been able to describe these atypical flaring events. On the other hand, an electron-positron pair plasma at the base of the AGN jet was proposed as the mechanism of bulk acceleration of relativistic outflows. This plasma in quasi-thermal equilibrium called Wein fireball emits radiation at MeV-peak energies serving as target of accelerated protons. In this work we describe the "orphan" TeV flares presented in blazars 1ES 1959+650 and Mrk 421 assuming geometrical considerations in the jet and evoking the interactions of Fermi-accelerated protons and MeV-peak target photons coming from the Wein fireball. After describing successfully these "orphan" TeV flares, we correlate the TeV γ-ray, neutrino and UHECR fluxes through pγ interactions and calculate the number of high-energy neutrinos and UHECRs expected in IceCube/AMANDA and TA experiment, respectively. In addition, thermal MeV neutrinos produced mainly through electron-positron annihilation at the Wein fireball will be able to propagate through it. By considering two- (solar, atmospheric and accelerator parameters) and three-neutrino mixing, we study the resonant oscillations and estimate the neutrino flavor ratios as well as the number of thermal neutrinos expected on Earth.
Lee, Eungkyu; Zhang, Teng; Hu, Ming; Luo, Tengfei
2016-06-22
Interfacial thermal resistance presents great challenges to the thermal management of modern electronics. In this work, we perform an analytical study to enhance the thermal boundary conductance (TBC) of nanostructured interfaces with square-shape pillar arrays, extendable to the characteristic lengths that can be fabricated in practice. As a representative system, we investigate a SiC substrate with the square-shape pillar array combined with epitaxial GaN as the nanostructured interface. By applying a first-order ray tracing method and molecular dynamics simulations to analyze phonon incidence and transmission at the nanostructured interface, we systematically study the impact of the characteristic dimensions of the pillar array on the TBC. Based on the multi-scale analysis we provide a general guideline to optimize the nanostructured interfaces to achieve higher TBC, demonstrating that the optimized TBC value of the nanostructured SiC/GaN interfaces can be 42% higher than that of the planar SiC/GaN interfaces without nanostructures. The model used and results obtained in this study will guide the further experimental realization of nanostructured interfaces for better thermal management in microelectronics. PMID:27275647
NASA Astrophysics Data System (ADS)
Quigley, Mark Francis
Effective temperatures, gravities, and surface abundances are determined for five central stars of planetary nebulae (CSPN): NGC 6826, NGC 2392, IC 2149, IC 4593, and IC 418. These stellar parameters are obtained by reproducing high resolution International Ultraviolet Explorer (IUE) spectra (1200-1680A), using atmospheric models which assume conditions of non-local thermodynamic equilibrium. In a preliminary study, absorption features are identified for the standard white subdwarf stars BD+28 ^circ4211 and BD+75 ^circ325, and B0 main sequence standard star Tau Sco, which exhibit effective temperatures (T _{rm eff}) of 80,000K, 55,000K, and 30,000K, respectively. Using the atomic data tables of Kurucz, and those of Ekberg and Johansson, over 98% of the absorption features in high resolution IUE spectra (1150-1990A) are identified. Analysis of the identifications shows that the UV spectra of these stars, similar in temperature to CSPN, are dominated by iron and nickel. The results of a comparative study of the high resolution UV spectra (1150-1980A) spectra of fifteen CSPN (36,000K <= T_{ rm eff} <= 130,000K) are also presented. Measurement of the terminal velocities of the stellar wind P Cygni profiles exhibited by the resonance lines of N V (1240A), Si IV (1390, 1400A), and C IV (1550A) yields estimates of stellar mass and radius. A grid of plane parallel model atmospheres in hydrostatic and statistical equilibrium is calculated, using complete linearization/accelerated lambda iteration hybrid algorithms. The major constituents of the atmospheres, hydrogen, helium, carbon, nitrogen, and oxygen, are treated non-local thermal equilibrium. Using these models, the spectra of the five coolest CSPN are reproduced over the wavelength region 1200-1680A, thus yielding estimates of the effective temperature, gravity, and surface abundances. For each atomic species, the total opacity is calculated, using atmospheres of identical composition and constant luminosity. Analysis
Marsh, Herbert W; Pekrun, Reinhard; Lichtenfeld, Stephanie; Guo, Jiesi; Arens, A Katrin; Murayama, Kou
2016-08-01
Ever since the classic research of Nicholls (1976) and others, effort has been recognized as a double-edged sword: while it might enhance achievement, it undermines academic self-concept (ASC). However, there has not been a thorough evaluation of the longitudinal reciprocal effects of effort, ASC, and achievement, in the context of modern self-concept theory and statistical methodology. Nor have there been developmental equilibrium tests of whether these effects are consistent across the potentially volatile early-to-middle adolescence. Hence, focusing on mathematics, we evaluate reciprocal effects models (REMs) over the first 4 years of secondary school (grades 5-8), relating effort, achievement (test scores and school grades), ASC, and ASC × Effort interactions for a representative sample of 3,144 German students (Mage = 11.75 years at Wave 1). ASC, effort, and achievement were positively correlated at each wave, and there was a clear pattern of positive reciprocal positive effects among ASC, test scores, and school grades-each contributing to the other, after controlling for the prior effects of all others. There was an asymmetrical pattern of effects for effort that is consistent with the double-edged sword premise: prior school grades had positive effects on subsequent effort, but prior effort had nonsignificant or negative effects on subsequent grades and ASC. However, on the basis of a synergistic application of new theory and methodology, we predicted and found a significant ASC × Effort interaction, such that prior effort had more positive effects on subsequent ASC and school grades when prior ASC was high-thus providing a key to breaking the double-edged sword. (PsycINFO Database Record PMID:27455188
NASA Astrophysics Data System (ADS)
Binder, Moritz; Barthel, Thomas
2015-09-01
For the simulation of equilibrium states and finite-temperature response functions of strongly correlated quantum many-body systems, we compare the efficiencies of two different approaches in the framework of the density matrix renormalization group (DMRG). The first is based on matrix product purifications. The second, more recent one, is based on so-called minimally entangled typical thermal states (METTS). For the latter, we highlight the interplay of statistical and DMRG truncation errors, discuss the use of self-averaging effects, and describe schemes for the computation of response functions. For critical as well as gapped phases of the spin-1 /2 XXZ chain and the one-dimensional Bose-Hubbard model, we assess the computation costs and accuracies of the two methods at different temperatures. For almost all considered cases, we find that, for the same computation cost, purifications yield more accurate results than METTS—often by orders of magnitude. The METTS algorithm becomes more efficient only for temperatures well below the system's energy gap. The exponential growth of the computation cost in the evaluation of response functions limits the attainable time scales in both methods and we find that in this regard, METTS do not outperform purifications.
NASA Astrophysics Data System (ADS)
Ahmad, Zahoor
2009-08-01
Cascaded arc of Pilot-PSI is modeled using numerical simulation code PLASIMO [G. M. Janssen, Ph.D. thesis, Eindhoven University of Technology (2000), http://plasimo.phys.tue.nl]. Pilot-PSI is a linear device used to produce a high density plasma column for the study of plasma surface interaction processes. In this modeling effort nonlocal thermal equilibrium plasma of Ar-H2 mixture is used. The purpose of these simulations is to optimize the cascaded arc for a higher yield of H+ ions and to investigate the role of Ar-H2 mixture ratios. The associative charge exchange reaction followed by dissociative recombination plays a very important role in the dissociation of H2 molecules and as a consequence the yield of H+ increases and of Ar+ decreases. The Ar+ density also decreases in the arc when H2 concentration is increased beyond certain value. With a mixture of 2.5 standard liters per minute Ar and 0.5 SLM H2 the H+ ion flux exceeds the flux obtained in pure H2 gas, at a reduced expenditure of energy per ion.
Lucà-Moretti, M; Grandi, A; Lucà, E; Muratori, G; Nofroni, M G; Mucci, M P; Gambetta, P; Stimolo, R; Drago, P; Giudice, G; Tamburlin, N; Karbalai, M; Valente, C; Moras, G
2003-01-01
Results of this multicentric study have shown that by giving Master Amino acid Pattern (MAP) as a sole and total substitute of dietary proteins to 500 overweight participants undergoing the American Nutrition Clinics/Overweight Management Program (ANC/OMP), the participants' body nitrogen balance could be maintained in equilibrium with essentially no calories (MAP 1 g=0.04 kcal), thereby preserving the body's structural and functional proteins, eliminating excessive water retention from the interstitial compartment, and preventing the sudden weight increase after study conclusion commonly known as the yo-yo effect. Study results have shown that the use of MAP, in conjunction with the ANC/OMP regimen, has proven to be safe and effective by preventing those adverse effects associated with a negative nitrogen balance, such as oversized or flabby tissue, stretch marks, the sagging of breast tissue, increased hair loss, faded hair color, and fragile or brittle nails. Also prevented were those anomalies commonly associated with weight-loss diets, such as hunger, weakness, headache caused by ketosis, constipation, and decreased libido. The use of MAP in conjunction with the ANC/OMP also allowed for mean weight loss of 2.5 kg (5.5 lb) per week, achieved through reduction of excessive fat tissue and elimination of excessive water retention from the interstitial compartment. PMID:14964347
NASA Astrophysics Data System (ADS)
Salyk, C.; Pontoppidan, K. M.; Blake, G. A.; Najita, J. R.; Carr, J. S.
2011-04-01
We present an analysis of Spitzer Infrared Spectrograph observations of H2O, OH, HCN, C2H2, and CO2 emission, and Keck-NIRSPEC observations of CO emission, from a diverse sample of T Tauri and Herbig Ae/Be circumstellar disks. We find that detections and strengths of most mid-IR molecular emission features are correlated with each other, suggesting a common origin and similar excitation conditions for this mid-infrared line forest. Aside from the remarkable differences in molecular line strengths between T Tauri, Herbig Ae/Be, and transitional disks discussed in Pontoppidan et al., we note that the line detection efficiency is anti-correlated with the 13/30 μm spectral slope, which is a measure of the degree of grain settling in the disk atmosphere. We also note a correlation between detection efficiency and Hα equivalent width, and tentatively with accretion rate, suggesting that accretional heating contributes to line excitation. If detected, H2O line fluxes are correlated with the mid-IR continuum flux, and other co-varying system parameters, such as L sstarf. However, significant sample variation, especially in molecular line ratios, remains, and its origin has yet to be explained. Local thermal equilibrium (LTE) models of the H2O emission show that line strength is primarily related to the best-fit emitting area, and this accounts for most source-to-source variation in H2O emitted flux. Best-fit temperatures and column densities cover only a small range of parameter space, near ~1018 cm-2 and 450 K for all sources, suggesting a high abundance of H2O in many planet-forming regions. Other molecules have a range of excitation temperatures from ~500to1500 K, also consistent with an origin in planet-forming regions. We find molecular ratios relative to water of ~10-3 for all molecules, with the exception of CO, for which n(CO)/n(H2O) ~ 1. However, LTE fitting caveats and differences in the way thermo-chemical modeling results are reported make comparisons with
Salyk, C.; Pontoppidan, K. M.; Blake, G. A.; Najita, J. R.; Carr, J. S.
2011-04-20
We present an analysis of Spitzer Infrared Spectrograph observations of H{sub 2}O, OH, HCN, C{sub 2}H{sub 2}, and CO{sub 2} emission, and Keck-NIRSPEC observations of CO emission, from a diverse sample of T Tauri and Herbig Ae/Be circumstellar disks. We find that detections and strengths of most mid-IR molecular emission features are correlated with each other, suggesting a common origin and similar excitation conditions for this mid-infrared line forest. Aside from the remarkable differences in molecular line strengths between T Tauri, Herbig Ae/Be, and transitional disks discussed in Pontoppidan et al., we note that the line detection efficiency is anti-correlated with the 13/30 {mu}m spectral slope, which is a measure of the degree of grain settling in the disk atmosphere. We also note a correlation between detection efficiency and H{alpha} equivalent width, and tentatively with accretion rate, suggesting that accretional heating contributes to line excitation. If detected, H{sub 2}O line fluxes are correlated with the mid-IR continuum flux, and other co-varying system parameters, such as L{sub *}. However, significant sample variation, especially in molecular line ratios, remains, and its origin has yet to be explained. Local thermal equilibrium (LTE) models of the H{sub 2}O emission show that line strength is primarily related to the best-fit emitting area, and this accounts for most source-to-source variation in H{sub 2}O emitted flux. Best-fit temperatures and column densities cover only a small range of parameter space, near {approx}10{sup 18} cm{sup -2} and 450 K for all sources, suggesting a high abundance of H{sub 2}O in many planet-forming regions. Other molecules have a range of excitation temperatures from {approx}500to1500 K, also consistent with an origin in planet-forming regions. We find molecular ratios relative to water of {approx}10{sup -3} for all molecules, with the exception of CO, for which n(CO)/n(H{sub 2}O) {approx} 1. However, LTE
NASA Astrophysics Data System (ADS)
Nishino, Masamichi; Miyashita, Seiji
2015-04-01
It is crucially important to investigate the effects of temperature on magnetic properties such as critical phenomena, nucleation, pinning, domain wall motion, and coercivity. The Landau-Lifshitz-Gilbert (LLG) equation has been applied extensively to study dynamics of magnetic properties. Approaches of Langevin noises have been developed to introduce the temperature effect into the LLG equation. To have the thermal equilibrium state (canonical distribution) as the steady state, the system parameters must satisfy some condition known as the fluctuation-dissipation relation. In inhomogeneous magnetic systems in which spin magnitudes are different at sites, the condition requires that the ratio between the amplitude of the random noise and the damping parameter depend on the magnitude of the magnetic moment at each site. Focused on inhomogeneous magnetic systems, we systematically showed agreement between the stationary state of the stochastic LLG equation and the corresponding equilibrium state obtained by Monte Carlo simulations in various magnetic systems including dipole-dipole interactions. We demonstrated how violations of the condition result in deviations from the true equilibrium state. We also studied the characteristic features of the dynamics depending on the choice of the parameter set. All the parameter sets satisfying the condition realize the same stationary state (equilibrium state). In contrast, different choices of parameter set cause seriously different relaxation processes. We show two relaxation types, i.e., magnetization reversals with uniform rotation and with nucleation.
NASA Technical Reports Server (NTRS)
Ferrante, J.
1972-01-01
Equilibrium surface segregation of aluminum in a copper-10-atomic-percent-aluminum single crystal alloy oriented in the /111/ direction was demonstrated by using Auger electron spectroscopy. This crystal was in the solid solution range of composition. Equilibrium surface segregation was verified by observing that the aluminum surface concentration varied reversibly with temperature in the range 550 to 850 K. These results were curve fitted to an expression for equilibrium grain boundary segregation and gave a retrieval energy of 5780 J/mole (1380 cal/mole) and a maximum frozen-in surface coverage three times the bulk layer concentration. Analyses concerning the relative merits of sputtering calibration and the effects of evaporation are also included.
NASA Technical Reports Server (NTRS)
Massaglia, S.; Ferrari, A.; Bodo, G.; Kalkofen, W.; Rosner, R.
1985-01-01
The stability of current-driven filamentary modes in magnetic flux tubes embedded in a plane-parallel atmosphere in LTE and in hydrostatic equilibrium is discussed. Within the tube, energy transport by radiation only is considered. The dominant contribution to the opacity is due to H- ions and H atoms (in the Paschen continuum). A region in the parameter space of the equilibrium configuration in which the instability is effective is delimited, and the relevance of this process for the formation of structured coronae in late-type stars and accretion disks is discussed.
NASA Astrophysics Data System (ADS)
Tychkov, Nikolay; Agashev, Alexey; Malygina, Elena; Pokhilenko, Nikolay
2014-05-01
Integrated study of 250 peridotite xenoliths from Udachnaya -East pipe show difference in mineral paragenesises and textural-structural peculiarities in the different level of cratonic lithosphere mantle (CLM). The compositions of minerals were determined using EPMA. Thermobarometric parameters (Brey, Kohller, 1990) were determined for all rocks occupying different fields on geothermal curve. The deepest layer (the pressure interval of 5.0-7.0 GPa) contains mostly pophyroclastic lherzolites. Anyway, some rocks of this layer have an idiomorphic texture being also enriched in incompatible components. Higher in the CLM sequence, the interval (4.2-6.3 GPa) is composed of the most depleted rocks: megacristalline ultradepleted harzburgite-dunites and depleted granular harzburgite-dunites, as well as lherzolites in a subordinate amount. They correspond strate to 35 mW/m2 and partly overlap the deeper layer in dapth. It is likely that rocks of this layer are in equilibrium and were not subject to significant secondary changes due to kimberlite magma intrusion. Thus, this interval of the CLM sequence reflects the true (relic) geotherm for the area of the Udachnaya kimberlite pipe. Moreover, it is obvious that this interval was a major supplier of diamonds into kimberlites of the Udachnaya pipe. The interval of 4.2-2.0 GPa in the CLM sequence is also composed of coarse depleted lherzolites and harzburgites. Rocks of this interval are slightly more enriched than those of the underlying interval. This is confirmed by the distinct predominance of lherzolites over harzburgite-dunites. The heat flow in this layer varies in the range of 38-45 mW/m2 and shows a general tendency to increase with decreasing depth. According to occurrence of nonequilibrium mineral assemblages and increased heat flow relative to the major heat flow of 35 mW/m2, this interval is similar to the deepest interval of secondary enriched rocks. Interval of less than 2.0 GPa composed of spinel lherzolites and
NASA Astrophysics Data System (ADS)
Agarwal, Shilpi; Rana, Puneet
2016-04-01
In this paper, we examine a layer of Oldroyd-B nanofluid for linear and nonlinear regimes under local thermal non-equilibrium conditions for the classical Rayleigh-Bénard problem. The free-free boundary condition has been implemented with the flux for nanoparticle concentration being zero at edges. The Oberbeck-Boussinesq approximation holds good and for the rotational effect Coriolis term is included in the momentum equation. A two-temperature model explains the effect of local thermal non-equilibrium among the particle and fluid phases. The criteria for onset of stationary convection has been derived as a function of the non-dimensionalized parameters involved including the Taylor number. The assumed boundary conditions negate the possibility of overstability due to the absence of opposing forces responsible for it. The thermal Nusselt number has been obtained utilizing a weak nonlinear theory in terms of various pertinent parameters in the steady and transient mode, and has been depicted graphically. The main findings signify that the rotation has a stabilizing effect on the system. The stress relaxation parameter λ_1 inhibits whereas the strain retardation parameter λ_2 exhibits heat transfer utilizing Al2O3 nanofluids.
Yu, Xiaoli; Sun, Zheng; Huang, Rui; Zhang, Yu; Huang, Yuqi
2015-01-01
Thermal effects such as conduction, convection and viscous dissipation are important to lubrication performance, and they vary with the friction conditions. These variations have caused some inconsistencies in the conclusions of different researchers regarding the relative contributions of these thermal effects. To reveal the relationship between the contributions of the thermal effects and the friction conditions, a steady-state THD analysis model was presented. The results indicate that the contribution of each thermal effect sharply varies with the Reynolds number and temperature. Convective effect could be dominant under certain conditions. Additionally, the accuracy of some simplified methods of thermo-hydrodynamic analysis is further discussed. PMID:26244665
NASA Astrophysics Data System (ADS)
Izzo, Dario; Petazzi, Lorenzo
2006-08-01
We present a satellite path planning technique able to make identical spacecraft aquire a given configuration. The technique exploits a behaviour-based approach to achieve an autonomous and distributed control over the relative geometry making use of limited sensorial information. A desired velocity is defined for each satellite as a sum of different contributions coming from generic high level behaviours: forcing the final desired configuration the behaviours are further defined by an inverse dynamic calculation dubbed Equilibrium Shaping. We show how considering only three different kind of behaviours it is possible to acquire a number of interesting formations and we set down the theoretical framework to find the entire set. We find that allowing a limited amount of communication the technique may be used also to form complex lattice structures. Several control feedbacks able to track the desired velocities are introduced and discussed. Our results suggest that sliding mode control is particularly appropriate in connection with the developed technique.
NASA Astrophysics Data System (ADS)
Birrer, Marcel; Stemmer, Christian; Adams, Nikolaus N.
2011-05-01
Investigations of hypersonic boundary-layer flows around a cubical obstacle with a height in the order of half the boundary layer thickness were carried out in this work. Special interest was laid on the influence of chemical non-equilibrium effects on the wake flow of the obstacle. Direct numerical simulations were conducted using three different gas models, a caloric perfect, an equilibrium and a chemical non-equilibrium gas model. The geometry was chosen as a wedge with a six degree half angle, according to the aborted NASA HyBoLT free flight experiment. At 0.5 m downstream of the leading edge, a surface trip was positioned. The free-stream flow was set to Mach 8.5 with air conditions taken from the 1976 standard atmosphere at an altitude of 42 km according to the predicted flight path. The simulations were done in three steps for all models. First, two-dimensional calculations of the whole configuration including the leading edge and the obstacle were conducted. These provide constant span-wise profiles for detailed, steady three-dimensional simulations around the close vicinity of the obstacle. A free-stream Mach number of about 6.3 occurs behind the shock. A cross-section in the wake of the object then delivers the steady inflow for detailed unsteady simulations of the wake. Perturbations at unstable frequencies, obtained from a bi-global secondary stability analysis, were added to these profiles. The solutions are time-Fourier transformed to investigate the unsteady downstream development of the different modes due to the interaction with the base-flow containing two counter-rotating vortices. Results will be presented that show the influence of the presence of chemical non-equilibrium on the instability in the wake of the object leading to a laminar or a turbulent wake.
NASA Astrophysics Data System (ADS)
Wang, Yu-Wei; Tesdahl, Curtis; Owens, Jim; Dorn, David
2012-06-01
Advancements in uncooled microbolometer technology over the last several years have opened up many commercial applications which had been previously cost prohibitive. Thermal technology is no longer limited to the military and government market segments. One type of thermal sensor with low NETD which is available in the commercial market segment is the uncooled amorphous silicon (α-Si) microbolometer image sensor. Typical thermal security cameras focus on providing the best image quality by auto tonemaping (contrast enhancing) the image, which provides the best contrast depending on the temperature range of the scene. While this may provide enough information to detect objects and activities, there are further benefits of being able to estimate the actual object temperatures in a scene. This thermographic ability can provide functionality beyond typical security cameras by being able to monitor processes. Example applications of thermography[2] with thermal camera include: monitoring electrical circuits, industrial machinery, building thermal leaks, oil/gas pipelines, power substations, etc...[3][5] This paper discusses the methodology of estimating object temperatures by characterizing/calibrating different components inside a thermal camera utilizing an uncooled amorphous silicon microbolometer image sensor. Plots of system performance across camera operating temperatures will be shown.
ArF processing of 90-nm design rule lithography achieved through enhanced thermal processing
NASA Astrophysics Data System (ADS)
Kagerer, Markus; Miller, Daniel; Chang, Wayne; Williams, Daniel J.
2006-03-01
As the lithography community has moved to ArF processing on 300 mm wafers for 90 nm design rules the process characterization of the components of variance continues to highlight the thermal requirements for the post exposure bake (PEB) processing step. In particular as the thermal systems have become increasingly uniform, the transient behavior of the thermal processing system has received the focus of attention. This paper demonstrates how a newly designed and patented thermal processing system was optimized for delivering improved thermal uniformity during a typical 90 second PEB processing cycle, rather than being optimized for steady state performance. This was accomplished with the aid of a wireless temperature measurement wafer system for obtaining real time temperature data and by using a response surface model (RSM) experimental design for optimizing parameters of the temperature controller of the thermal processing system. The new units were field retrofitted seamlessly in <2 days at customer sites without disruption to process recipes or flows. After evaluating certain resist parameters such as PEB temperature sensitivity and post exposure delay (PED) - stability of the baseline process, the new units were benchmarked against the previous PEB plates by processing a split lot experiment. Additional hardware characterization included environmental factors such as air velocity in the vicinity of the PEB plates and transient time between PEB and chill plate. At the completion of the optimization process, the within wafer CD uniformity displayed a significant improvement when compared to the previous hardware. The demonstrated within wafer CD uniformity improved by 27% compared to the initial hardware and baseline process. ITRS requirements for the 90 nm node were exceeded.
Baldwin, Christopher L; Bigelow, Nicholas W; Masiello, David J
2014-04-17
A consequence of thermal diffusion is that heat, even when applied to a localized region of space, has the tendency to produce a temperature change that is spatially uniform throughout a material with a thermal conductivity that is much larger than that of its environment. This implies that the degree of spatial correlation between the heat power supplied and the temperature change that it induces is likely to be small. Here, we show, via theory and simulation, that through a Fano interference, temperature changes can be both localized and controllably directed within certain plasmon-supporting metal nanoparticle assemblies. This occurs even when all particles are composed of the same material and contained within the same diffraction-limited spot. These anomalous thermal properties are compared and contrasted across three different nanosystems, the coupled nanorod-antenna, the heterorod dimer, and the nanocube on a substrate, known to support both spatial and spectral Fano interferences. We conclude that the presence of a Fano resonance is not sufficient by itself to induce a controllably nanolocalized temperature change. However, when present in a nanosystem of the right composition and morphology, temperature changes can be manipulated with nanoscale precision, despite thermal diffusion. PMID:26269978
Teeter, G.
2007-01-01
In this study, polycrystalline Cu-foil substrates are exposed to elemental Te vapor at substrate temperatures below 373 K. Auger electron spectroscopy measurements indicate that copper-telluride films are formed at the substrate surface that have a 2:1 Cu-to-Te ratio, as predicted by the Cu--Te phase diagram. When these films are annealed above about 700 K in vacuum, Te desorbs from the substrate with zero-order kinetics. An analysis of Te-desorption traces that assumes the reaction Cu{sub 2}Te(s) {yields} 2Cu(s) + {alpha}Te(?) + 1/2(1 - {alpha})Te2({nu}) finds a thermal-decomposition activation energy of 217 {+-} 3 kJ mol{sup -1}. These Te-desorption data are compared to the Te impingement rate calculated from Cu{sub 2}Te equilibrium vapor-pressure data from the literature and found to be in excellent agreement.
An upwind, kinetic flux-vector splitting method for flows in chemical and thermal non-equilibrium
NASA Technical Reports Server (NTRS)
Eppard, W. M.; Grossman, B.
1993-01-01
We have developed new upwind kinetic difference schemes for flows with non-equilibrium thermodynamics and chemistry. These schemes are derived from the Boltzmann equation with the resulting Euler schemes developed as moments of the discretized Boltzmann scheme with a locally Maxwellian velocity distribution. Splitting the velocity distribution at the Boltzmann level is seen to result in a flux-split Euler scheme and is called Kinetic Flux Vector Splitting (KFVS). Extensions to flows with finite-rate chemistry and vibrational relaxation is accomplished utilizing nonequilibrium kinetic theory. Computational examples are presented comparing KFVS with the schemes of Van Leer and Roe for a quasi-one-dimensional flow through a supersonic diffuser, inviscid flow through two-dimensional inlet, and viscous flow over a cone at zero angle-of-attack. Calculations are also shown for the transonic flow over a bump in a channel and the transonic flow over an NACA 0012 airfoil. The results show that even though the KFVS scheme is a Riemann solver at the kinetic level, its behavior at the Euler level is more similar to the existing flux-vector splitting algorithms than to the flux-difference splitting scheme of Roe.
NASA Astrophysics Data System (ADS)
Feldman, Michal; Tennenholtz, Moshe
We introduce partition equilibrium and study its existence in resource selection games (RSG). In partition equilibrium the agents are partitioned into coalitions, and only deviations by the prescribed coalitions are considered. This is in difference to the classical concept of strong equilibrium according to which any subset of the agents may deviate. In resource selection games, each agent selects a resource from a set of resources, and its payoff is an increasing (or non-decreasing) function of the number of agents selecting its resource. While it has been shown that strong equilibrium exists in resource selection games, these games do not possess super-strong equilibrium, in which a fruitful deviation benefits at least one deviator without hurting any other deviator, even in the case of two identical resources with increasing cost functions. Similarly, strong equilibrium does not exist for that restricted two identical resources setting when the game is played repeatedly. We prove that for any given partition there exists a super-strong equilibrium for resource selection games of identical resources with increasing cost functions; we also show similar existence results for a variety of other classes of resource selection games. For the case of repeated games we identify partitions that guarantee the existence of strong equilibrium. Together, our work introduces a natural concept, which turns out to lead to positive and applicable results in one of the basic domains studied in the literature.
NASA Astrophysics Data System (ADS)
Gelet, R.; Loret, B.; Khalili, N.
2012-07-01
The constitutive thermo-hydro-mechanical equations of fractured media are embodied in the theory of mixtures applied to three-phase poroelastic media. The solid skeleton contains two distinct cavities filled with the same fluid. Each of the three phases is endowed with its own temperature. The constitutive relations governing the thermomechanical behavior, generalized diffusion and transfer are structured by, and satisfy, the dissipation inequality. The cavities exchange both mass and energy. Mass exchanges are driven by the jump in scaled chemical potential, and energy exchanges by the jump in coldness. The finite element approximation uses the displacement vector, the two fluid pressures and the three temperatures as primary variables. It is used to analyze a generic hot dry rock geothermal reservoir. Three parameters of the model are calibrated from the thermal outputs of Fenton Hill and Rosemanowes HDR reservoirs. The calibrated model is next applied to simulate circulation tests at the Fenton Hill HDR reservoir. The finer thermo-hydro-mechanical response provided by the dual porosity model with respect to a single porosity model is highlighted in a parameter analysis. Emphasis is put on the influence of the fracture spacing, on the effective stress response and on the permeation of the fluid into the porous blocks. The dual porosity model yields a thermally induced effective stress that is less tensile compared with the single porosity response. This effect becomes significant for large fracture spacings. In agreement with field data, fluid loss is observed to be high initially and to decrease with time.
NASA Astrophysics Data System (ADS)
Moreno, Paola
Buildings, especially in hot climates, consume a lot of energy when people want to be comfortable inside them, which translates to very expensive fees each month. The most innovative response to this problem is renewable energy, that is used, in this case, to run mechanical HVAC systems. Renewable energy is the solution for many problems, but to avoid urban heat islands when using excessive HVAC systems (powered by renewables), and to solve thermal comfort-related problems, there has to be other solution. The major challenge to find it would be to have a change of thinking process. If a building in a hot-arid region uses natural processes to emulate the functions of HVAC systems, and the proper passive strategies, then, it will provide thermal comfort to its users, diminishing the need of a mechanical system. This hypothesis will be carried out by extracting the natural processes found in a specific case in nature, applying them into a building's design, and then simulating its energy efficiency with the adequate software. There will be a comparison of the same proposed building without the natural processes, to have tangible numbers showing that these proposed strategies, in fact, work. With explanatory detailed diagrams and the energy analysis, the hypothesis could be proven correct or incorrect. The significance of this approach relies on the proximity to the natural processes that have been working in different aspects of life since the beginning of time. They have been there all the time, waiting until architects, engineers, and people in general use them, instead of making more new energy-using inventions. By having the numbers from a conventional building and the ones of the proposed building, and the right environmental diagrams, the experiment should be valid. In the near future, there should be more research focused on nature and its processes, in order to be able to reduce the use of mechanical systems, and with that, reduce the energy use and the carbon
Lucà-Moretti, M; Grandi, A; Lucà, E; Muratori, G; Nofroni, M G; Mucci, M P; Gambetta, P; Stimolo, R; Drago, P; Giudice, G; Tamburlin, N
2003-01-01
Results of this multicentric study have shown that by giving 10 g (10 tablets) of Master Amino acid Pattern (MAP) as a substitute for dietary proteins, once a day, to 114 overweight participants undergoing the American Nutrition Clinics/Overweight Management Program (ANC/OMP), the participants' nitrogen balance could be maintained in equilibrium with essentially no calories (MAP 1 g=0.04 kcal), thereby preserving the body's structural and functional proteins, eliminating excessive water retention from the interstitial compartment, and preventing the sudden weight increase after study conclusion commonly known as the yo-yo effect. Study results have shown that the use of MAP, in conjunction with the ANC/OMP, has proven to be safe and effective by preventing those adverse effects associated with a negative nitrogen balance, such as oversized or flabby tissue, stretch marks, sagging of breast tissue, increased hair loss, faded hair color, and fragile or brittle nails. Also preventing those anomalies commonly associated with weight-loss diets, such as hunger, weakness, headache caused by ketosis, constipation, or decreased libido, the use of MAP, in conjunction with the ANC/OMP, allowed for mean weight loss of 1.4 kg (3 lb) per week. PMID:14964348
Yoshikawa, S.
1981-08-01
A straight, helical plasma equilibrium equation is solved numerically for a plasma with a helical magnetic axis. As is expected, by a suitable choice of the plasma boundary, the vacuum configuration is made line ..integral.. dl/B stable. As the plasma pressure increases, the line ..integral.. dl/B criterion will improve (again as expected). There is apparently no limit on the plasma ..beta.. from the equilibrium consideration. Thus helical-axis stellarator ..beta.. will presumably be limited by MHD stability ..beta.., and not by equilibrium ..beta...
Narra, Sudhakar; Shigeto, Shinsuke
2015-03-01
Low-lying excited triplet states of aromatic carbonyl compounds exhibit diverse photophysical and photochemical properties of fundamental importance. Despite tremendous effort in studying those triplet states, the effects of substituents and solvents on the energetics of the triplet manifold and on photoreactivity remain to be fully understood. We have recently studied the ordering of the low-lying nπ* and ππ* excited triplet states and its substituent dependence in acetophenone derivatives using nanosecond time-resolved near-IR (NIR) spectroscopy. Here we address the other important issue, the solvent effects, by directly observing the electronic bands in the NIR that originate from the lowest nπ* and ππ* states of acetophenone derivatives in four solvents of different polarity (n-heptane, benzene, acetonitrile, and methanol). The two transient NIR bands decay synchronously in all the solvents, indicating that the lowest nπ* and ππ* states are in thermal equilibrium irrespective of the solvent polarity studied here. We found that the ππ* band increases in intensity relative to the nπ* band as solvent polarity increases. These results are compared with the photoreduction rate constant for the acetophenone derivatives in the solvents to which 2-propanol was added as a hydrogen-atom donor. Based on the present findings, we present a comprehensive, solvent- and substituent-dependent energy level diagram of the low-lying nπ* and ππ* excited triplet states. PMID:25686256
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.
Kumar, Venkatraman Ravi; Rajkumar, Nagappan; Ariese, Freek; Umapathy, Siva
2015-10-01
The photochemistry of aromatic ketones plays a key role in various physicochemical and biological processes, and solvent polarity can be used to tune their triplet state properties. Therefore, a comprehensive analysis of the conformational structure and the solvent polarity induced energy level reordering of the two lowest triplet states of 9,10-phenanthrenequinone (PQ) was carried out using nanosecond-time-resolved absorption (ns-TRA), time-resolved resonance Raman (TR(3)) spectroscopy, and time dependent-density functional theory (TD-DFT) studies. The ns-TRA of PQ in acetonitrile displays two bands in the visible range, and these two bands decay with similar lifetime at least at longer time scales (μs). Interestingly, TR(3) spectra of these two bands indicate that the kinetics are different at shorter time scales (ns), while at longer time scales they followed the kinetics of ns-TRA spectra. Therefore, we report a real-time observation of the thermal equilibrium between the two lowest triplet excited states of PQ, assigned to nπ* and ππ* of which the ππ* triplet state is formed first through intersystem crossing. Despite the fact that these two states are energetically close and have a similar conformational structure supported by TD-DFT studies, the slow internal conversion (∼2 ns) between the T(2)(1(3)nπ*) and T(1)(1(3)ππ*) triplet states indicates a barrier. Insights from the singlet excited states of PQ in protic solvents [ J. Chem. Phys. 2015 , 142 , 24305 ] suggest that the lowest nπ* and ππ* triplet states should undergo hydrogen bond weakening and strengthening, respectively, relative to the ground state, and these mechanisms are substantiated by TD-DFT calculations. We also hypothesize that the different hydrogen bonding mechanisms exhibited by the two lowest singlet and triplet excited states of PQ could influence its ISC mechanism. PMID:26381591
Rauscher, Emily; Showman, Adam P.
2014-04-01
As a planet ages, it cools and its radius shrinks at a rate set by the efficiency with which heat is transported from the interior out to space. The bottleneck for this transport is at the boundary between the convective interior and the radiative atmosphere; the opacity there sets the global cooling rate. Models of planetary evolution are often one dimensional (1D), such that the radiative-convective boundary (RCB) is defined by a single temperature, pressure, and opacity. In reality the spatially inhomogeneous stellar heating pattern and circulation in the atmosphere could deform the RCB, allowing heat from the interior to escape more efficiently through regions with lower opacity. We present an analysis of the degree to which the RCB could be deformed and the resultant change in the evolutionary cooling rate. In this initial work we calculate the upper limit for this effect by comparing an atmospheric structure in local radiative equilibrium to its 1D equivalent. We find that the cooling through an uneven RCB could be enhanced over cooling through a uniform RCB by as much as 10%-50%. We also show that the deformation of the RCB (and the enhancement of the cooling rate) increases with a greater incident stellar flux or a lower inner entropy. Our results indicate that this mechanism could significantly change a planet's thermal evolution, causing it to cool and shrink more quickly than would otherwise be expected. This may exacerbate the well-known difficulty in explaining the very large radii observed for some hot Jupiters.
NASA Astrophysics Data System (ADS)
Guzella, Matheus dos Santos; Cabezas-Gómez, Luben; da Silva, José Antônio; Maia, Cristiana Brasil; Hanriot, Sérgio de Morais
2016-02-01
This study presents a numerical evaluation of the influence of some void fraction correlations over the thermal-hydraulic behavior of wire-on-tube condensers operating with HFC-134a. The numerical model is based on finite volume method considering the homogeneous equilibrium model. Empirical correlations are applied to provide closure relations. Results show that the choice of void fraction correlation influences the refrigerant charge and pressure drop calculations, while no influences the heat transfer rate.
Zeroth Law, Entropy, Equilibrium, and All That
ERIC Educational Resources Information Center
Canagaratna, Sebastian G.
2008-01-01
The place of the zeroth law in the teaching of thermodynamics is examined in the context of the recent discussion by Gislason and Craig of some problems involving the establishment of thermal equilibrium. The concept of thermal equilibrium is introduced through the zeroth law. The relation between the zeroth law and the second law in the…
Wang, Shipan; Zhang, Yuewei; Chen, Weiping; Wei, Jinbei; Liu, Yu; Wang, Yue
2015-08-01
Achieving high power efficiencies at high-brightness levels is still an important issue for organic light-emitting diodes (OLEDs) based on the thermally activated delayed fluorescence (TADF) mechanism. Herein, enhanced electroluminescence efficiencies were achieved in fluorescent OLEDs using a TADF molecule, (4s,6s)-2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN), as a host and quinacridone derivatives (QA) as fluorescent dopants. PMID:26120606
NASA Astrophysics Data System (ADS)
Beck, C.; Rezaei, R.; Puschmann, K. G.
2013-01-01
Context. The Ca II H line is one of the strongest lines in the solar spectrum, and it provides continuous information on the solar atmosphere from the photosphere to the lower chromosphere. Aims: We describe an inversion approach that reproduces observed Ca II H spectra by assuming local thermal equilibrium (LTE). Methods: We developed an inversion strategy based on the SIR code that reproduces Ca II H spectra in the LTE approximation. The approach uses a two-step procedure with an archive of pre-calculated spectra to fit the line core and a subsequent iterative modification to improve the fit mainly in the line wing. Simultaneous spectra in the 630 nm range can optionally be used to fix the continuum temperature. The method retrieves one-dimensional (1D) temperature stratifications while neglecting lateral radiative transport. Line-of-sight velocities are included post facto with an empirical approach. Results: An archive of about 300 000 pre-calculated spectra is more than sufficient to reproduce the line core of observed Ca II H spectra both in the quiet Sun and in active regions. The subsequent iterative adjustment of the thermodynamical stratification matches observed and best-fit spectra to a level of about 0.5% of Ic in the line wing and about 1% of Ic in the line core. Conclusions: The successful application of the LTE inversion strategy suggests that inversion schemes based on pre-calculated spectra allow a reliable and relatively fast retrieval of solar properties from observed chromospheric spectra. The approach can be easily extended to a 1D non-LTE (NLTE) case by a simple exchange of the pre-calculated archive spectra. Using synthetic NLTE spectra from numerical three-dimensional (3D) simulations instead will finally allow one to extend the approach from the static 1D-case to dynamical atmosphere models, including the complete 3D radiative transport. The animation is available in electronic form at http://www.aanda.org
Tuning universality far from equilibrium
Karl, Markus; Nowak, Boris; Gasenzer, Thomas
2013-01-01
Possible universal dynamics of a many-body system far from thermal equilibrium are explored. A focus is set on meta-stable non-thermal states exhibiting critical properties such as self-similarity and independence of the details of how the respective state has been reached. It is proposed that universal dynamics far from equilibrium can be tuned to exhibit a dynamical transition where these critical properties change qualitatively. This is demonstrated for the case of a superfluid two-component Bose gas exhibiting different types of long-lived but non-thermal critical order. Scaling exponents controlled by the ratio of experimentally tuneable coupling parameters offer themselves as natural smoking guns. The results shed light on the wealth of universal phenomena expected to exist in the far-from-equilibrium realm. PMID:23928853
Phonon Mapping in Flowing Equilibrium
NASA Astrophysics Data System (ADS)
Ruff, J. P. C.
2015-03-01
When a material conducts heat, a modification of the phonon population occurs. The equilibrium Bose-Einstein distribution is perturbed towards flowing-equilibrium, for which the distribution function is not analytically known. Here I argue that the altered phonon population can be efficiently mapped over broad regions of reciprocal space, via diffuse x-ray scattering or time-of-flight neutron scattering, while a thermal gradient is applied across a single crystal sample. When compared to traditional transport measurements, this technique offers a superior, information-rich new perspective on lattice thermal conductivity, wherein the band and momentum dependences of the phonon thermal current are directly resolved. The proposed method is benchmarked using x-ray thermal diffuse scattering measurements of single crystal diamond under transport conditions. CHESS is supported by the NSF & NIH/NIGMS via NSF Award DMR-1332208.
NASA Astrophysics Data System (ADS)
Wei, Yong; Xu, Shan; Huang, Chenghui; Chen, Weidong; Zhuang, Fengjiang; Huang, Lingxiong; Chen, Zhenqiang; Zhang, Ge
2012-09-01
The negative and positive thermal focal lengths for 1047 nm and 1053 nm were respectively demonstrated through analyzing different thermal lensing effects along the π- and σ-polarizations in a plane-parallel resonator. A compact and efficient diode-end-pumped 1053 nm Nd:YLF polarized laser is presented. As high as 11.2 W output power of the polarized 1053 nm laser has been obtained at an absorbed pump power of 22.3 W with an optical-optical efficiency of 50% and a slope efficiency of 53%. With the aid of a ray propagation matrix and a λ/4 wave plate, different thermal lensing effects for the π- and σ-polarizations have been theoretically analyzed and experimentally verified.
NASA Astrophysics Data System (ADS)
Wolff, Andrzej
2010-01-01
The temperature of a brake friction surface influences significantly the braking effectiveness. The paper describes a heat transfer process in car brakes. Using a developed program of finite element method, the temperature distributions in brake rotors (disc and drum brake) of a light truck have been calculated. As a preliminary consistency criterion of the brake thermal state in road and roll-stand braking conditions, a balance of the energy cumulated in the brake rotor has been taken into account. As the most reliable consistency criterion an equality of average temperatures of the friction surface has been assumed. The presented method allows to achieve on a roll-stand the analogical thermal states of automotive brakes, which are observed during braking in road conditions. Basing on this method, it is possible to calculate the braking time and force for a high-speed roll-stand. In contrast to the previous papers of the author, new calculation results have been presented.
NASA Astrophysics Data System (ADS)
Klepikova, Maria V.; Le Borgne, Tanguy; Bour, Olivier; Hochreutener, Rebecca; Lavenant, Nicolas
2015-04-01
The prediction of transport patterns in fractured media is a challenging task. Different transport mechanisms are generally contributing: dispersion at fracture scale related to aperture variability, dispersion at network scale due to transport in different flowpaths and matrix diffusion. It is however difficult to know which mechanism is dominant. In this study we test the interest of heat tracer tests for providing new constraints on transport in fractured media by interpreting three push-pull tests of different duration. A series of heat and solute push-pull tracer test with Dirac-type injection was conducted in fractured aquifer of Ploemeur, France. The comparison of solute and heat breakthrough curves shows that due to thermal loss to the rock matrix temperature recovery peak arrives earlier than concentration peak. Moreover, the peak is significantly smaller for temperature recovery while it exhibits a longest tailing. Finally, we found that the recovered peak temperature decreases with scale and has a power law slope of -1 on a log-log plot. By means of flow and heat numerical model, we investigate the relevance of different conceptual models: single 'plate', 'tube' and 'ellipse' homogeneous fracture models at different scales. For all tested fracture geometries temperature breakthrough curves were found to be sensitive to fracture aperture. An 'elliptical tube' fracture model was found to provide the best fit to the data and based on this model, we were able to estimate the aperture of the fracture in the present case. Moreover, the comparison of experimental breakthrough curves and modelling results also suggests that the effective fracture aperture may increase with scale. This work emphasizes that multiple-scale push-pull thermal tests can provide valuable insights on fracture geometry and fracture aperture.
How Far from Equilibrium Is Active Matter?
NASA Astrophysics Data System (ADS)
Fodor, Étienne; Nardini, Cesare; Cates, Michael E.; Tailleur, Julien; Visco, Paolo; van Wijland, Frédéric
2016-07-01
Active matter systems are driven out of thermal equilibrium by a lack of generalized Stokes-Einstein relation between injection and dissipation of energy at the microscopic scale. We consider such a system of interacting particles, propelled by persistent noises, and show that, at small but finite persistence time, their dynamics still satisfy a time-reversal symmetry. To do so, we compute perturbatively their steady-state measure and show that, for short persistent times, the entropy production rate vanishes. This endows such systems with an effective fluctuation-dissipation theorem akin to that of thermal equilibrium systems. Last, we show how interacting particle systems with viscous drags and correlated noises can be seen as in equilibrium with a viscoelastic bath but driven out of equilibrium by nonconservative forces, hence providing energetic insight into the departure of active systems from equilibrium.
Anderson, J.C.
1992-03-01
Temperatures were monitored at various locations on DT-18 and PC-1 shipping packages during furnace tests at the Y-12 Plant in Oak Ridge, Tennessee. The furnace tests are intended to simulate hypothetical thermal accident conditions specified in Title 10 CFR, Pt. 71.73 (c)(3). Maximum temperatures of the outer containers ranged from 750 to 965{degrees}C while typical maximum temperatures recorded on the inner containers were 60 to 77{degrees}C. One exceptionally high temperature of 196{degrees}C occurred on the PC-1 inner container. Heating 7.1 models of both the DT-18 and PC-1 packages were developed. Models with and without heat generation in the inner containers were developed for each shipping package. The models with heat generation are intended to simulate condensation and convection of hot vapors generated during the heating of the Celotex{trademark} insulating material used in the packages. In general, the analytical models calculate temperatures for the outer containers which agree well with the test data. The HEATING models with and without heat generation bound the inner container test data. These findings are significant in that they lead to the conclusion that heat is transferred to the inner containers through a mechanism other than conduction alone. The high temperature of 196{degrees}C recorded at the PC-1 inner container is within 4{degrees}C of the maximum temperature calculated by the PC-1 HEATING model with heat generation.
Mixed quantum-classical equilibrium in global flux surface hopping
Sifain, Andrew E.; Wang, Linjun; Prezhdo, Oleg V.
2015-06-14
Global flux surface hopping (GFSH) generalizes fewest switches surface hopping (FSSH)—one of the most popular approaches to nonadiabatic molecular dynamics—for processes exhibiting superexchange. We show that GFSH satisfies detailed balance and leads to thermodynamic equilibrium with accuracy similar to FSSH. This feature is particularly important when studying electron-vibrational relaxation and phonon-assisted transport. By studying the dynamics in a three-level quantum system coupled to a classical atom in contact with a classical bath, we demonstrate that both FSSH and GFSH achieve the Boltzmann state populations. Thermal equilibrium is attained significantly faster with GFSH, since it accurately represents the superexchange process. GFSH converges closer to the Boltzmann averages than FSSH and exhibits significantly smaller statistical errors.
Sahu, J.N.; Patwardhan, A.V.; Meikap, B.C.
2009-03-15
Ammonia has long been known to be useful in the treatment of flue/tail/stack gases from industrial furnaces, incinerators, and electric power generation industries. In this study, urea hydrolysis for production of ammonia, in different application areas that require safe use of ammonia at in situ condition, was investigated in a batch reactor. The equilibrium and kinetic study of urea hydrolysis was done in a batch reactor at reaction pressure to investigate the effect of reaction temperature, initial feed concentration, and time on ammonia production. This study reveals that conversion increases exponentially with an increase in temperature but with increases in initial feed concentration of urea the conversion decreases marginally. Further, the effect of time on conversion has also been studied; it was found that conversion increases with increase in time. Using collision theory, the temperature dependency of forward rate constant developed from which activation energy of the reaction and the frequency factor has been calculated. The activation energy and frequency factor of urea hydrolysis reaction at atmospheric pressure was found to be 73.6 kJ/mol and 2.89 x 10{sup 7} min{sup -1}, respectively.
Pathak, Amar Deep; Nedea, Silvia; Zondag, Herbert; Rindt, Camilo; Smeulders, David
2016-04-21
Salt hydrates store solar energy in chemical form via a reversible dehydration-hydration reaction. However, as a side reaction to dehydration, hydrolysis (HCl formation) may occur in chloride based salt hydrates (specially in MgCl2 hydrates), affecting the durability of the storage system. The mixture of CaCl2 and MgCl2 hydrates has been shown experimentally to have exceptional cycle stability and improved kinetics. However, the optimal operating conditions for the mixture are unknown. To understand the appropriate balance between dehydration and hydrolysis kinetics in the mixtures, it is essential to gain in-depth insight into the mixture components. We present a GGA-DFT level study to investigate the various gaseous structures of CaCl2 hydrates and to understand the relative stability of their conformers. The hydration strength and relative stability of conformers are dominated by electrostatic interactions. A wide network of intramolecular homonuclear and heteronuclear hydrogen bonds is observed in CaCl2 hydrates. Equilibrium product concentrations are obtained during dehydration and hydrolysis reactions under various temperature and pressure conditions. The trend of the dehydration curve with temperature in CaCl2 hydrates is similar to the experiments. Comparing these results to those of MgCl2 hydrates, we find that CaCl2 hydrates are more resistant towards hydrolysis in the temperature range of 273-800 K. Specifically, the present study reveals that the onset temperatures of HCl formation, a crucial design parameter for MgCl2 hydrates, are lower than for CaCl2 hydrates except for the mono-hydrate. PMID:27004734
Thermal Motion of DNA in an MspA Pore.
Lu, Bo; Fleming, Stephen; Szalay, Tamas; Golovchenko, Jene
2015-10-01
We report on an experiment and calculations that determine the thermal motion of a voltage-clamped single-stranded DNA-NeutrAvidin complex in a Mycobacterium smegmatis porin A nanopore. The electric force and diffusion constant of DNA inside a Mycobacterium smegmatis porin A pore were determined to evaluate the thermal position fluctuations of DNA. We show that an out-of-equilibrium state returns to equilibrium so quickly that experiments usually measure a weighted average over the equilibrium position distribution. Averaging over the equilibrium position distribution is consistent with results of state-of-the-art nanopore sequencing experiments. It is shown how a reduction in thermal position fluctuations can be achieved by increasing the electrophoretic force used in nanopore sequencing devices. PMID:26445444
NASA Astrophysics Data System (ADS)
Bu, Minqiang; Perch-Nielsen, Ivan R.; Sørensen, Karen S.; Skov, Julia; Sun, Yi; Duong Bang, Dang; Pedersen, Michael E.; Hansen, Mikkel F.; Wolff, Anders
2013-07-01
We present a temperature control method capable of effectively shortening the thermal cycling time of polymerase chain reaction (PCR) in a disposable polymer microfluidic device with an external heater and a temperature sensor. The method employs optimized temperature overshooting and undershooting steps to achieve a rapid ramping between the temperature steps for DNA denaturation, annealing and extension. The temperature dynamics within the microfluidic PCR chamber was characterized and the overshooting and undershooting parameters were optimized using the temperature-dependent fluorescence signal from Rhodamine B. The method was validated with the PCR amplification of mecA gene (162 bp) from methicillin-resistant Staphylococcus aureus bacterium (MRSA), where the time for 30 cycles was reduced from 50 min (without over- and undershooting) to 20 min.
Equilibrium fluctuation energy of gyrokinetic plasma
Krommes, J.A.; Lee, W.W.; Oberman, C.
1985-11-01
The thermal equilibrium electric field fluctuation energy of the gyrokinetic model of magnetized plasma is computed, and found to be smaller than the well-known result
Non-equilibrium Transport of Light
NASA Astrophysics Data System (ADS)
Wang, Chiao-Hsuan; Taylor, Jacob
Non-equilibrium Transport of Light The thermalization of light under conditions of parametric coupling to a bath provides a robust chemical potential for light. We study non-equilibrium transport of light using non-equilibrium Green's function approach under the parametric coupling scheme, and explore a potential photonic analogue to the Landauer transport equation. Our results provide understandings of many-body states of photonic matter with chemical potential imbalances. The transport theory of light paves the way for quantum simulation and even practical applications of diode-like circuits using quantum photonic sources in the microwave and optical domain.
Passive equilibrium studies on ZT-P
Pickrell, M.M.; Reass, W.A.
1987-12-01
The poloidal field system of ZT-P was modified by the addition of a transformer, which coupled the magnetizing and equilibrium circuits. ZT-P is a small, air core, Reversed Field Pinch, operated at the Los Alamos National Laboratory. It is used as test bed for the much larger ZT-H, RFP experiment, now under construction at LANL. Planned experiments include size scaling measurements and determining the effect of low time constant measurements and determining the effect of low time constant shell operation. ZT-P has had an entirely passive equilibrium system, which did not provide a well centered equilibrium, although a tolerable equilibrium was realized by removing half of the equilibrium coil set. The transformer was added to the poloidal field system to adjust the equilibrium current for a centered plasma, while using the entire coil set. It also had the effect of reducing the dependence of the equilibrium on the plasma resistance. Stable, well centered discharges were achieved over a broad range of plasma currents. The improved equilibrium also lowered the loop voltage and extended the discharge lifetime. These experiments also investigated the unique problems of equilibrium systems on air core RFP devices. 26 refs., 6 figs.
Pions in and out of equilibrium
Gavin, S.
1991-12-01
Can final state scattering wrestle the secondaries in nucleus-nucleus collisions into a fluid state near local thermal equilibrium What do the pion p{sub T} spectra measured in pp, pA and SPS light ion experiments already tell us about the approach to equilibrium To begin to address these questions, we must face the nonequilibrium nature of hadronic evolution in the late stages of these collisions. I will outline efforts to apply transport theory to the nonequilibrium pion fluid at midrapidity focusing on two phenomena: partial thermalization and pion conservation.
Pions in and out of equilibrium
Gavin, S.
1991-12-01
Can final state scattering wrestle the secondaries in nucleus-nucleus collisions into a fluid state near local thermal equilibrium? What do the pion p{sub T} spectra measured in pp, pA and SPS light ion experiments already tell us about the approach to equilibrium? To begin to address these questions, we must face the nonequilibrium nature of hadronic evolution in the late stages of these collisions. I will outline efforts to apply transport theory to the nonequilibrium pion fluid at midrapidity focusing on two phenomena: partial thermalization and pion conservation.
Getting Freshman in Equilibrium.
ERIC Educational Resources Information Center
Journal of Chemical Education, 1983
1983-01-01
Various aspects of chemical equilibrium were discussed in six papers presented at the Seventh Biennial Conference on Chemical Education (Stillwater, Oklahoma 1982). These include student problems in understanding hydrolysis, helping students discover/uncover topics, equilibrium demonstrations, instructional strategies, and flaws to kinetic…
Quantum fields out of thermal equilibrium
Eboli, O.; Jackiw, R.; Pi, S.
1988-06-15
The isoentropic, but energy-nonconserving, time evolution of mixed quantum states is studied in quantum mechanics and quantum field theory. A variational principle, which gives the Liouville--von Neumann equation, is implemented approximately by making a Gaussian Ansatz for the density matrix. The dynamical equations governing the parameters that define the Ansatz satisfy equations variously analogous to the Schroedinger equation and to mechanical problems. Interesting nonequilibrium evolution is found in special cases, as, for example, when the analog Schroedinger equation gives rise to reflectionless transmission. For field theory in an external, time-dependent metric we obtain equations that were previously derived in the many-field (spherical-model) limit.
Chemical Principles Revisited: Chemical Equilibrium.
ERIC Educational Resources Information Center
Mickey, Charles D.
1980-01-01
Describes: (1) Law of Mass Action; (2) equilibrium constant and ideal behavior; (3) general form of the equilibrium constant; (4) forward and reverse reactions; (5) factors influencing equilibrium; (6) Le Chatelier's principle; (7) effects of temperature, changing concentration, and pressure on equilibrium; and (8) catalysts and equilibrium. (JN)
Computing Equilibrium Chemical Compositions
NASA Technical Reports Server (NTRS)
Mcbride, Bonnie J.; Gordon, Sanford
1995-01-01
Chemical Equilibrium With Transport Properties, 1993 (CET93) computer program provides data on chemical-equilibrium compositions. Aids calculation of thermodynamic properties of chemical systems. Information essential in design and analysis of such equipment as compressors, turbines, nozzles, engines, shock tubes, heat exchangers, and chemical-processing equipment. CET93/PC is version of CET93 specifically designed to run within 640K memory limit of MS-DOS operating system. CET93/PC written in FORTRAN.
Equilibrium time correlation functions and the dynamics of fluctuations
Luban, Marshall; Luscombe, James H.
1999-12-01
Equilibrium time correlation functions are of great importance because they probe the equilibrium dynamical response to external perturbations. We discuss the properties of time correlation functions for several systems that are simple enough to illustrate the calculational steps involved. The discussion underscores the need for avoiding language which misleadingly suggests that thermal equilibrium is associated with a quiescent or moribund state of the system. (c) 1999 American Association of Physics Teachers.
Theory for non-equilibrium statistical mechanics.
Attard, Phil
2006-08-21
This paper reviews a new theory for non-equilibrium statistical mechanics. This gives the non-equilibrium analogue of the Boltzmann probability distribution, and the generalization of entropy to dynamic states. It is shown that this so-called second entropy is maximized in the steady state, in contrast to the rate of production of the conventional entropy, which is not an extremum. The relationships of the new theory to Onsager's regression hypothesis, Prigogine's minimal entropy production theorem, the Langevin equation, the formula of Green and Kubo, the Kawasaki distribution, and the non-equilibrium fluctuation and work theorems, are discussed. The theory is worked through in full detail for the case of steady heat flow down an imposed temperature gradient. A Monte Carlo algorithm based upon the steady state probability density is summarized, and results for the thermal conductivity of a Lennard-Jones fluid are shown to be in agreement with known values. Also discussed is the generalization to non-equilibrium mechanical work, and to non-equilibrium quantum statistical mechanics. As examples of the new theory two general applications are briefly explored: a non-equilibrium version of the second law of thermodynamics, and the origin and evolution of life. PMID:16883388
Computing Properties Of Chemical Mixtures At Equilibrium
NASA Technical Reports Server (NTRS)
Mcbride, B. J.; Gordon, S.
1995-01-01
Scientists and engineers need data on chemical equilibrium compositions to calculate theoretical thermodynamic properties of chemical systems. Information essential in design and analysis of such equipment as compressors, turbines, nozzles, engines, shock tubes, heat exchangers, and chemical-processing equipment. CET93 is general program that calculates chemical equilibrium compositions and properties of mixtures for any chemical system for which thermodynamic data are available. Includes thermodynamic data for more than 1,300 gaseous and condensed species and thermal-transport data for 151 gases. Written in FORTRAN 77.
NASA Astrophysics Data System (ADS)
Li, Angsheng; Zhang, Xiaohui; Pan, Yicheng; Peng, Pan
2014-12-01
It seems a universal phenomenon of networks that the attacks on a small number of nodes by an adversary player Alice may generate a global cascading failure of the networks. It has been shown (Li et al., 2013) that classic scale-free networks (Barabási and Albert, 1999, Barabási, 2009) are insecure against attacks of as small as O(logn) many nodes. This poses a natural and fundamental question: Can we introduce a second player Bob to prevent Alice from global cascading failure of the networks? We proposed a game in networks. We say that a network has an equilibrium game if the second player Bob has a strategy to balance the cascading influence of attacks by the adversary player Alice. It was shown that networks of the preferential attachment model (Barabási and Albert, 1999) fail to have equilibrium games, that random graphs of the Erdös-Rényi model (Erdös and Rényi, 1959, Erdös and Rényi, 1960) have, for which randomness is the mechanism, and that homophyly networks (Li et al., 2013) have equilibrium games, for which homophyly and preferential attachment are the underlying mechanisms. We found that some real networks have equilibrium games, but most real networks fail to have. We anticipate that our results lead to an interesting new direction of network theory, that is, equilibrium games in networks.
Stabilization of beam-weibel instability by equilibrium density ripples
Mishra, S. K. Kaw, Predhiman; Das, A.; Sengupta, S.; Ravindra Kumar, G.
2014-01-15
In this paper, we present an approach to achieve suppression/complete stabilization of the transverse electromagnetic beam Weibel instability in counter streaming electron beams by modifying the background plasma with an equilibrium density ripple, shorter than the skin depth; this weakening is more pronounced when thermal effects are included. On the basis of a linear two stream fluid model, it is shown that the growth rate of transverse electromagnetic instabilities can be reduced to zero value provided certain threshold values for ripple parameters are exceeded. We point out the relevance of the work to recent experimental investigations on sustained (long length) collimation of fast electron beams and integral beam transport for laser induced fast ignition schemes, where beam divergence is suppressed with the assistance of carbon nano-tubes.
Novel procedure for thermal equilibration in molecular dynamics simulation.
Gallo, Marco T; Grant, Barry J; Teodoro, Miguel L; Melton, Julia; Cieplak, Piotr; Phillips, George N; Stec, Boguslaw
2009-04-01
We describe a simple novel procedure for achieving thermal equilibration between a protein and a surrounding solvent during molecular dynamics (MD) simulation. The method uniquely defines the length of simulation time required to achieve thermal equilibrium over a broad range of parameters, thus removing ambiguities associated with the traditional heuristic approaches. The proposed protocol saves simulation time and avoids bias introduced by the inclusion of non-equilibrium events. The key element of the procedure involves coupling only the solvent atoms to a standard heat bath. Measuring progress towards thermal equilibration involves simply monitoring the difference in temperature between the solvent and the protein. Here, we report that the results of MD simulations using the above procedure are measurably improved relative to the traditional approaches in terms of root-mean-square deviations and principal components analysis both indicating significantly less undesirable divergence. PMID:25125797
Novel procedure for thermal equilibration in molecular dynamics simulation
Gallo, Marco T.; Grant, Barry J.; Teodoro, Miguel L.; Melton, Julia; Cieplak, Piotr; Phillips, George N.; Stec, Boguslaw
2014-01-01
We describe a simple novel procedure for achieving thermal equilibration between a protein and a surrounding solvent during molecular dynamics (MD) simulation. The method uniquely defines the length of simulation time required to achieve thermal equilibrium over a broad range of parameters, thus removing ambiguities associated with the traditional heuristic approaches. The proposed protocol saves simulation time and avoids bias introduced by the inclusion of non-equilibrium events. The key element of the procedure involves coupling only the solvent atoms to a standard heat bath. Measuring progress towards thermal equilibration involves simply monitoring the difference in temperature between the solvent and the protein. Here, we report that the results of MD simulations using the above procedure are measurably improved relative to the traditional approaches in terms of root-mean-square deviations and principal components analysis both indicating significantly less undesirable divergence. PMID:25125797
Equilibrium-like phase transition of a dynamic system
NASA Astrophysics Data System (ADS)
Han, Ming; Yan, Jing; Granick, Steve; Luijten, Erik
2014-03-01
Dynamic systems are considered to be intrinsically different from systems in thermal equilibrium. Despite this fundamental dichotomy, here we demonstrate that a non-equilibrium, fully dynamical system can display behavior that constitutes a complete analogy to thermal equilibrium phase behavior. This dynamical system, consisting of Janus colloids strongly controlled by external fields and over-damped by a viscous solvent, phase separates like a binary fluid mixture, with a coexistence curve separating mixed and demixed regimes and a critical point that we demonstrate to belong to the 2D Ising universality class. Within the coexistence curve, we locate the spinodal curve that separates spinodal decomposition from nucleation and growth.
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.
An Updated Equilibrium Machine
ERIC Educational Resources Information Center
Schultz, Emeric
2008-01-01
A device that can demonstrate equilibrium, kinetic, and thermodynamic concepts is described. The device consists of a leaf blower attached to a plastic container divided into two chambers by a barrier of variable size and form. Styrofoam balls can be exchanged across the barrier when the leaf blower is turned on and various air pressures are…
An Updated Equilibrium Machine
NASA Astrophysics Data System (ADS)
Schultz, Emeric
2008-08-01
A device that can demonstrate equilibrium, kinetic, and thermodynamic concepts is described. The device consists of a leaf blower attached to a plastic container divided into two chambers by a barrier of variable size and form. Styrofoam balls can be exchanged across the barrier when the leaf blower is turned on and various air pressures are applied. Equilibrium can be approached from different distributions of balls in the container under different conditions. The Le Châtelier principle can be demonstrated. Kinetic concepts can be demonstrated by changing the nature of the barrier, either changing the height or by having various sized holes in the barrier. Thermodynamic concepts can be demonstrated by taping over some or all of the openings and restricting air flow into container on either side of the barrier.
NASA Technical Reports Server (NTRS)
Shebalin, John V.
1997-01-01
The entropy associated with absolute equilibrium ensemble theories of ideal, homogeneous, fluid and magneto-fluid turbulence is discussed and the three-dimensional fluid case is examined in detail. A sigma-function is defined, whose minimum value with respect to global parameters is the entropy. A comparison is made between the use of global functions sigma and phase functions H (associated with the development of various H-theorems of ideal turbulence). It is shown that the two approaches are complimentary though conceptually different: H-theorems show that an isolated system tends to equilibrium while sigma-functions allow the demonstration that entropy never decreases when two previously isolated systems are combined. This provides a more complete picture of entropy in the statistical mechanics of ideal fluids.
The equilibrium dayside magnetosphere
NASA Technical Reports Server (NTRS)
Zavriyev, Anton; Hasegawa, Akira
1989-01-01
A method is presented of computing the dayside global earth magnetic field which is in equilibrium with the plasma pressure, based on satellite observations at a local region of the magnetosphere. The method, which utilizes a perturbation around a dipole magnetic field, involves computation of the global plasma pressure profile based on the equatorial (anisotropic) pressure data, derivation of the current profile which satisfies the equilibrium condition, and computation of the magnetic field using the current profile and the boundary current produced by the solar wind. The method is applied for the Active Magnetospheric Particle Tracer Explorers data, and the result of the computation is found to compare reasonably well with the observed magnetic field profile near the geomagnetic equator.
NASA Astrophysics Data System (ADS)
Godrèche, C.
2011-03-01
Preface; 1. Shape and growth of crystals P. Nozières; 2. Instabilities of planar solidification fronts B. Caroli, C. Caroli and B. Roulet; 3. An introduction to the kinetics of first-order phase transition J. S. Langer; 4. Dendritic growth and related topics Y. Pomeau and M. Ben Amar; 5. Growth and aggregation far from equilibrium L. M. Sander; 6. Kinetic roughening of growing surfaces J. Krug and H. Spohn; Acknowledgements; References; Index.
Exoplanet Equilibrium Chemistry Calculations
NASA Astrophysics Data System (ADS)
Blumenthal, Sarah; Harrington, J.; Bowman, M.; Blecic, J.
2013-10-01
Recently, Agundez et al. (2012, A&A 548, A73) used a chemical kinetics code to study a model HD 209458b (equilibrium temperature of 1450 K, assuming full redistribution and 0 albedo). They found that thermochemistry dominates most of the dayside, but that significant compositional gradients may exist across the dayside. We calculate equilibrium-chemistry molecular abundances for several model exoplanets, using NASA's open-source Chemical Equilibrium Abundances code (McBride and Gordon 1996). We vary the degree of radiation redistribution to the dark side, ranging from total redistribution to instantaneous reradiation. Atomically, both the solar abundance multiple and the carbon fraction vary. Planet substellar temperatures range from just above 1200 K, where photochemistry should no longer be important, to those of hot planets (3000 K). We present synthetic abundance images for the key spectroscopic molecules CO, CH4, and H2O for several hot-Jupiter model planets. This work was supported by the NASA Planetary Atmospheres grant NNX12AI69G.
Equilibrium Electroconvective Instability
NASA Astrophysics Data System (ADS)
Rubinstein, I.; Zaltzman, B.
2015-03-01
Since its prediction 15 years ago, hydrodynamic instability in concentration polarization at a charge-selective interface has been attributed to nonequilibrium electro-osmosis related to the extended space charge which develops at the limiting current. This attribution had a double basis. On the one hand, it has been recognized that neither equilibrium electro-osmosis nor bulk electroconvection can yield instability for a perfectly charge-selective solid. On the other hand, it has been shown that nonequilibrium electro-osmosis can. The first theoretical studies in which electro-osmotic instability was predicted and analyzed employed the assumption of perfect charge selectivity for the sake of simplicity and so did the subsequent studies of various time-dependent and nonlinear features of electro-osmotic instability. In this Letter, we show that relaxing the assumption of perfect charge selectivity (tantamount to fixing the electrochemical potential of counterions in the solid) allows for the equilibrium electroconvective instability. In addition, we suggest a simple experimental test for determining the true, either equilibrium or nonequilibrium, origin of instability in concentration polarization.
Planetary cratering 2: Studies of saturation equilibrium
NASA Astrophysics Data System (ADS)
Hartmann, William K.; Gaskell, Robert W.
1997-01-01
A realistic computer model has been developed to display images of imaginary cratered surfaces, taking into account empirically measured input size distributions of primary and secondary craters, ejecta blanket morphology including feathering with distance, obliteration due to ejecta from outside the imaged area, lighting effects, etc. The model allows us to track surface evolution of morphology as new craters are added. Using the model as well as lunar photos, we have studied the approach to saturation equilibrium (defined as a condition when no further proportionate increase in crater density occurs as input cratering increases). We find that an identifiable saturation equilibrium occurs close to a level previously identified for this state (Hartmann 1984), typically fluctuating around a crater density from about 0.4 to 2 times that level. This result is fairly robust vis-a-vis the range of model parameters we have chosen. Flooding, basin ejecta blankets, and other obliterative effects can introduce structure and oscillations within this range, even after saturation equilibrium is achieved. These findings may constrain or revise certain earlier interpretations of satellite and planet surface evolution and impactor populations which were predicated on the assumed absence of saturation equilibrium. In our fourth experimental run, we found that suppression of "sandblasting" by sub-resolution impacts allows the smallest secondaries to rise above the saturation equilibrium line, a result that might be relevant to a similar situation on Gaspra and perhaps some other asteroids.
Approach to equilibrium in N-body gravitational systems
NASA Astrophysics Data System (ADS)
El-Zant, A. A.
1998-10-01
The evolution of closed gravitational systems is studied by means of N-body simulations. This, as well as being interesting in its own right, provides insight into the dynamical and statistical mechanical properties of gravitational systems: the possibility of the existence of stable equilibrium states and the associated relaxation time would provide an ideal situation where relaxation theory can be tested. Indeed, these states are found to exist for single mass N-body systems, and the condition for this is simply that obtained from elementary thermodynamical considerations applied to self-gravitating ideal gas spheres. However, even when this condition is satisfied, some initial states may not end as isothermal spheres. It is therefore only a necessary condition. Simple considerations also predict that, for fixed total mass, energy, and radius, stable isothermal spheres are unique. Therefore, statistically irreversible perturbations to the density profile, caused by the accumulation of massive particles near the center of multimass systems, destroy these equilibria if the aforementioned quantities are kept fixed. The time scale for this to happen was found to be remarkably short (a few dynamical times when N=2500) in systems undergoing violent relaxation. The time taken to achieve thermal equilibrium depended on the initial conditions and could be comparable to a dynamical time (even when the conditions for violent relaxation were not satisfied) or the two body relaxation time. The relaxation time for velocity anisotropies was intermediate between these two time scales, being long compared to the dynamical time but much (about four times) shorter than the time scale of energy relaxation. This last result, along with the observation of the anomalously rapid mass segregation in some situations, suggests that, in gravitational systems, different quantities may relax at different rates, and that the thermal (two body) relaxation time scale, even if accurate for energy
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
Structural design using equilibrium programming
NASA Technical Reports Server (NTRS)
Scotti, Stephen J.
1992-01-01
Multiple nonlinear programming methods are combined in the method of equilibrium programming. Equilibrium programming theory has been appied to problems in operations research, and in the present study it is investigated as a framework to solve structural design problems. Several existing formal methods for structural optimization are shown to actually be equilibrium programming methods. Additionally, the equilibrium programming framework is utilized to develop a new structural design method. Selected computational results are presented to demonstrate the methods.
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.
Liu, Xiaoyan; Su, Yiguo; Zhao, Qihang; Du, Chunfang; Liu, Zhiliang
2016-01-01
This work reports on the construction of a Bi24O31Cl10/BiOCl heterojunction via a simple thermal annealing method. The X-ray diffraction (XRD) results indicated that the phase transformation from BiOCl to Bi24O31Cl10 could be realized during the thermal annealing process. The high-resolution transmission electron microscopy (HRTEM) images, X-ray photoelectron spectroscopy (XPS) binding energy shifts, Raman spectra and Fouier transform infrared spectroscopy (FT-IR) spectra confirmed the formation of the Bi24O31Cl10/BiOCl heterojunction. The obtained Bi24O31Cl10/BiOCl photocatalyst showed excellent conversion efficiency and selectivity toward photocatalytic conversion of benzyl alcohol to benzaldehyde under visible light irradiation. The radical scavengers and electron spin resonance (ESR) results suggested that the photogenerated holes were the dominant reactive species responsible for the photocatalytic oxidation of benzyl alcohol and superoxide radicals were not involved in the photocatalytic process. The in-situ generation of Bi24O31Cl10/BiOCl heterojunction may own superior interfacial contact than the two-step synthesized heterojunctions, which promotes the transfer of photogenerated charge carriers and is favorable for excellent photocatalytic activities. PMID:27340032
NASA Astrophysics Data System (ADS)
Liu, Xiaoyan; Su, Yiguo; Zhao, Qihang; Du, Chunfang; Liu, Zhiliang
2016-06-01
This work reports on the construction of a Bi24O31Cl10/BiOCl heterojunction via a simple thermal annealing method. The X-ray diffraction (XRD) results indicated that the phase transformation from BiOCl to Bi24O31Cl10 could be realized during the thermal annealing process. The high-resolution transmission electron microscopy (HRTEM) images, X-ray photoelectron spectroscopy (XPS) binding energy shifts, Raman spectra and Fouier transform infrared spectroscopy (FT-IR) spectra confirmed the formation of the Bi24O31Cl10/BiOCl heterojunction. The obtained Bi24O31Cl10/BiOCl photocatalyst showed excellent conversion efficiency and selectivity toward photocatalytic conversion of benzyl alcohol to benzaldehyde under visible light irradiation. The radical scavengers and electron spin resonance (ESR) results suggested that the photogenerated holes were the dominant reactive species responsible for the photocatalytic oxidation of benzyl alcohol and superoxide radicals were not involved in the photocatalytic process. The in-situ generation of Bi24O31Cl10/BiOCl heterojunction may own superior interfacial contact than the two-step synthesized heterojunctions, which promotes the transfer of photogenerated charge carriers and is favorable for excellent photocatalytic activities.
Liu, Xiaoyan; Su, Yiguo; Zhao, Qihang; Du, Chunfang; Liu, Zhiliang
2016-01-01
This work reports on the construction of a Bi24O31Cl10/BiOCl heterojunction via a simple thermal annealing method. The X-ray diffraction (XRD) results indicated that the phase transformation from BiOCl to Bi24O31Cl10 could be realized during the thermal annealing process. The high-resolution transmission electron microscopy (HRTEM) images, X-ray photoelectron spectroscopy (XPS) binding energy shifts, Raman spectra and Fouier transform infrared spectroscopy (FT-IR) spectra confirmed the formation of the Bi24O31Cl10/BiOCl heterojunction. The obtained Bi24O31Cl10/BiOCl photocatalyst showed excellent conversion efficiency and selectivity toward photocatalytic conversion of benzyl alcohol to benzaldehyde under visible light irradiation. The radical scavengers and electron spin resonance (ESR) results suggested that the photogenerated holes were the dominant reactive species responsible for the photocatalytic oxidation of benzyl alcohol and superoxide radicals were not involved in the photocatalytic process. The in-situ generation of Bi24O31Cl10/BiOCl heterojunction may own superior interfacial contact than the two-step synthesized heterojunctions, which promotes the transfer of photogenerated charge carriers and is favorable for excellent photocatalytic activities. PMID:27340032
NASA Astrophysics Data System (ADS)
Xie, Fengxian; Zhang, Di; Choy, Wallace C. H.
2015-09-01
The lead halide-based perovskite solar cells have emerged as a promising candidate in photovoltaic applications. However, the precise control over the morphologiy of the perovskite films (minimizing pore formation) and enhanced stability and reproducibility of the devices remain challenging, even though both will be necessary for further advancements. Here we introduce vacuum-assisted thermal annealing as a means of controlling the composition and morphology of the CH3NH3PbI3 films formed from PbCl2 and CH3NH3I as precursors. We identify the critical role that the CH3NH3Cl generated as a byproduct during the pervoskite synthesis plays for the photovoltaic performance of the perovskite film. Removing this byproduct through vacuum-assisted thermal annealing we succeeded in producing pure, pore-free planar CH3NH3PbI3 films showing high conversion efficiency (PCE) reaching 14.5%). Removal of CH3NH3Cl strongly attenuate the photocurrent hysteresis.
Li, Shaopeng; Huang, Rongjin; Zhao, Yuqiang; Li, Wen; Wang, Wei; Huang, Chuanjun; Gong, Pifu; Lin, Zheshuai; Li, Laifeng
2015-08-17
Cubic La(Fe,Si)13-based compounds have been recently developed as promising negative thermal expansion(NTE) materials, but the narrow NTE operation-temperature window(∼110 K) restricts their actual applications. In this work, we demonstrate that the NTE operation-temperature window of LaFe(13-x)Si(x) can be significantly broadened by adjusting Fe-Fe magnetic exchange coupling as x ranges from 2.8 to 3.1. In particular, the NTE operation-temperature window of LaFe10.1Si2.9 is extended to 220 K. More attractively, the coefficients of thermal expansion of LaFe10.0Si3.0 and LaFe9.9Si3.1 are homogeneous in the NTE operation-temperature range of about 200 K, which is much valuable for the stability of fabricating devices. The further experimental characterizations combined with first-principles studies reveal that the tetragonal phase is gradually introduced into the cubic phase as the Si content increases, hence modifies the Fe-Fe interatomic distance. The reduction of the overall Fe-Fe magnetic exchange interactions contributes to the broadness of NTE operation-temperature window for LaFe(13-x)Si(x). PMID:26196377
Non-equilibrium DMFT - Polaritonics
NASA Astrophysics Data System (ADS)
Lubatsch, Andreas; Frank, Regine
Non-equilibrium physics recently really becomes important with the progress of ultrafast laser sciences. However in our understanding there is still a gap between equilibrium physics and the non-equilibrium, even though numerical methods have been advanced in recent years. We compare in this talk novel results at hand with equilibrium physics. The comparison will show that especially theoretical efforts are needed to explain many - so far - unresolved problems and to predict novel research on the basis of ab initio computing. We specifically discuss several non-equilibrium extensions of DMFT, numerical methods as well as semi-analytical solvers.
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.
Statistical physics ""Beyond equilibrium
Ecke, Robert E
2009-01-01
The scientific challenges of the 21st century will increasingly involve competing interactions, geometric frustration, spatial and temporal intrinsic inhomogeneity, nanoscale structures, and interactions spanning many scales. We will focus on a broad class of emerging problems that will require new tools in non-equilibrium statistical physics and that will find application in new material functionality, in predicting complex spatial dynamics, and in understanding novel states of matter. Our work will encompass materials under extreme conditions involving elastic/plastic deformation, competing interactions, intrinsic inhomogeneity, frustration in condensed matter systems, scaling phenomena in disordered materials from glasses to granular matter, quantum chemistry applied to nano-scale materials, soft-matter materials, and spatio-temporal properties of both ordinary and complex fluids.
Exploring Chemical Equilibrium in Hot Jovians
NASA Astrophysics Data System (ADS)
Blumenthal, Sarah; Harrington, Joseph; Mandell, Avi; Hébrard, Eric; Venot, Olivia; Cubillos, Patricio; Blecic, Jasmina; Challener, Ryan
2016-01-01
It has been established that equilibrium chemistry is usually achieved deep in the atmosphere of hot Jovians where timescales are short (Line and Yung 2013). Thus, equilibrium chemistry has been used as a starting point (setting initial conditions) for evaluating disequilibrium processes. We explore parameters of setting these initial conditions including departures from solar metallicity, the number of species allowed in a system, the types of species allowed in a system, and different thermodynamic libraries in an attempt to create a standard for evaluating equilibrium chemistry. NASA's open source code Chemical Equilibrium and Applications (CEA) is used to calculate model planet abundances by varying the metallicity, in the pressure regime 0.1 to 1 bar. These results are compared to a variety of exoplanets(Teq between 600 and 2100K) qualitatively by color maps of the dayside with different temperature redistributions. Additionally, CEA (with an up-dated thermodynamic library) is compared with the thermochemical model presented in Venotet al. (2012) for HD 209458b and HD 189733b. This same analysis is then applied to the cooler planet HD 97658b. Spectra are generated and we compare both models' outputs using the open source codetransit (https://github.com/exosports/transit) using the opacities of 15 molecules. We make the updated CEA thermodyanamic library and supporting Python scripts to do the CEA analyses available open source. Thiswork was supported by NASA Planetary Atmospheres grant NNX12AI69G.
Exploring Equilibrium Chemistry for Hot Exoplanets
NASA Astrophysics Data System (ADS)
Blumenthal, Sarah; Harrington, Joseph; Mandell, Avi; Hébrard, Eric; Venot, Olivia; Cubillos, Patricio; Challener, Ryan
2015-11-01
It has been established that equilibrium chemistry is usually achieved deep in the atmosphere of hot Jovians where timescales are short (Line and Young 2013). Thus, equilibrium chemistry has been used as a starting point (setting initial conditions) for evaluating disequilibrium processes. We explore parameters of setting these initial conditions including departures from solar metallicity, the number of species allowed in a system, the types of species allowed in a system, and different thermodynamic libraries in an attempt to create a standard for evaluating equilibrium chemistry. NASA's open source code Chemical Equilibrium and Applications (CEA) is used to calculate model planet abundances by varying the metallicity, in the pressure regime of 0.1 to 1 bar. These results are compared to a variety of exoplanets (Teq between 600 and 2100K) qualitatively by color maps of the dayside with different temperature redistributions. Additionally, CEA (with an updated thermodynamic library) is validated with the thermochemical model presented in Venot et al. (2012) for HD 209458b and HD 189733b. This same analysis has then been extended to the cooler planet HD 97658b. Spectra are generated from both models’ abundances using the open source code transit (https://github.com/exosports/transit) using the opacities of 15 molecules. We make the updated CEA thermodyanamic library and supporting Python scripts to do the CEA analyses available open source. This work was supported by NASA Planetary Atmospheres grant NNX12AI69G.
The Nash equilibrium: a perspective.
Holt, Charles A; Roth, Alvin E
2004-03-23
In 1950, John Nash contributed a remarkable one-page PNAS article that defined and characterized a notion of equilibrium for n- person games. This notion, now called the "Nash equilibrium," has been widely applied and adapted in economics and other behavioral sciences. Indeed, game theory, with the Nash equilibrium as its centerpiece, is becoming the most prominent unifying theory of social science. In this perspective, we summarize the historical context and subsequent impact of Nash's contribution. PMID:15024100
Grinding kinetics and equilibrium states
NASA Technical Reports Server (NTRS)
Opoczky, L.; Farnady, F.
1984-01-01
The temporary and permanent equilibrium occurring during the initial stage of cement grinding does not indicate the end of comminution, but rather an increased energy consumption during grinding. The constant dynamic equilibrium occurs after a long grinding period indicating the end of comminution for a given particle size. Grinding equilibrium curves can be constructed to show the stages of comminution and agglomeration for certain particle sizes.
Gritti, Fabrice; Gilar, Martin; Jarrell, Joseph A
2016-04-29
A cylindrical vacuum chamber (inner diameter 5 cm) housing a narrow-bore 2.1 mm×100 mm column packed with 1.8 μm HSS-T3 fully porous particles was built in order to isolate thermally the chromatographic column from the external air environment. Consistent with statistical physics and the mean free path of air molecules, the experimental results show that natural air convection and conduction are fully eliminated for housing air pressures smaller than 10(-4) Torr. Heat radiation is minimized by wrapping up the column with low-emissivity aluminum-tape (emissivity coefficient ϵ=0.03 vs. 0.28 for polished stainless steel 316). Overall, the heat flux at the column wall is reduced by 96% with respect to standard still-air ovens. From a practical viewpoint, the efficiency of the column run at a flow rate of 0.6 mL/min at a constant 13,000 psi pressure drop (the viscous heat power is around 9 W/m) is improved by up to 35% irrespective of the analyte retention. Models of heat and mass transfer reveal that (1) the amplitude of the radial temperature gradient is significantly reduced from 0.30 to 0.01 K and (2) the observed improvement in resolution power stems from a more uniform distribution of the flow velocity across the column diameter. The eddy dispersion term in the van Deemter equation is reduced by 0.8±0.1 reduced plate height unit, a significant gain in column performance. PMID:27040511
Phillips, Rob
2016-01-01
It has been said that the cell is the test tube of the twenty-first century. If so, the theoretical tools needed to quantitatively and predictively describe what goes on in such test tubes lag sorely behind the stunning experimental advances in biology seen in the decades since the molecular biology revolution began. Perhaps surprisingly, one of the theoretical tools that has been used with great success on problems ranging from how cells communicate with their environment and each other to the nature of the organization of proteins and lipids within the cell membrane is statistical mechanics. A knee-jerk reaction to the use of statistical mechanics in the description of cellular processes is that living organisms are so far from equilibrium that one has no business even thinking about it. But such reactions are probably too hasty given that there are many regimes in which, because of a separation of timescales, for example, such an approach can be a useful first step. In this article, we explore the power of statistical mechanical thinking in the biological setting, with special emphasis on cell signaling and regulation. We show how such models are used to make predictions and describe some recent experiments designed to test them. We also consider the limits of such models based on the relative timescales of the processes of interest. PMID:27429713
NASA Astrophysics Data System (ADS)
Phillips, Rob
2015-03-01
It has been said that the cell is the test tube of the twenty-first century. If so, the theoretical tools needed to quantitatively and predictively describe what goes on in such test tubes lag sorely behind the stunning experimental advances in biology seen in the decades since the molecular biology revolution began. Perhaps surprisingly, one of the theoretical tools that has been used with great success on problems ranging from how cells communicate with their environment and each other to the nature of the organization of proteins and lipids within the cell membrane is statistical mechanics. A knee-jerk reaction to the use of statistical mechanics in the description of cellular processes is that living organisms are so far from equilibrium that one has no business even thinking about it. But such reactions are probably too hasty given that there are many regimes in which, because of a separation of timescales, for example, such an approach can be a useful first step. In this article, we explore the power of statistical mechanical thinking in the biological setting, with special emphasis on cell signaling and regulation. We show how such models are used to make predictions and describe some recent experiments designed to test them. We also consider the limits of such models based on the relative timescales of the processes of interest.
Multi-period equilibrium/near-equilibrium in electricity markets based on locational marginal prices
NASA Astrophysics Data System (ADS)
Garcia Bertrand, Raquel
In this dissertation we propose an equilibrium procedure that coordinates the point of view of every market agent resulting in an equilibrium that simultaneously maximizes the independent objective of every market agent and satisfies network constraints. Therefore, the activities of the generating companies, consumers and an independent system operator are modeled: (1) The generating companies seek to maximize profits by specifying hourly step functions of productions and minimum selling prices, and bounds on productions. (2) The goals of the consumers are to maximize their economic utilities by specifying hourly step functions of demands and maximum buying prices, and bounds on demands. (3) The independent system operator then clears the market taking into account consistency conditions as well as capacity and line losses so as to achieve maximum social welfare. Then, we approach this equilibrium problem using complementarity theory in order to have the capability of imposing constraints on dual variables, i.e., on prices, such as minimum profit conditions for the generating units or maximum cost conditions for the consumers. In this way, given the form of the individual optimization problems, the Karush-Kuhn-Tucker conditions for the generating companies, the consumers and the independent system operator are both necessary and sufficient. The simultaneous solution to all these conditions constitutes a mixed linear complementarity problem. We include minimum profit constraints imposed by the units in the market equilibrium model. These constraints are added as additional constraints to the equivalent quadratic programming problem of the mixed linear complementarity problem previously described. For the sake of clarity, the proposed equilibrium or near-equilibrium is first developed for the particular case considering only one time period. Afterwards, we consider an equilibrium or near-equilibrium applied to a multi-period framework. This model embodies binary
Evans, R. F. L.; Fan, W. J.
2014-11-10
Thermally assisted magnetic writing is an important technology utilizing temperature dependent magnetic properties to enable orientation of a magnetic data storage medium. Using an atomistic spin model, we study non-equilibrium field cooled magnetization processes on sub-nanosecond timescales required for device applications. We encapsulate the essential physics of the process in a thermoremanent magnetization curve and show that for fast timescales, heating to the Curie temperature is necessary where the magnetic relaxation time is shortest. Furthermore, we demonstrate the requirement for large magnetic fields to achieve a high thermoremanent magnetization necessary for fast recording or data rates.
Rapid-Equilibrium Enzyme Kinetics
ERIC Educational Resources Information Center
Alberty, Robert A.
2008-01-01
Rapid-equilibrium rate equations for enzyme-catalyzed reactions are especially useful because if experimental data can be fit by these simpler rate equations, the Michaelis constants can be interpreted as equilibrium constants. However, for some reactions it is necessary to use the more complicated steady-state rate equations. Thermodynamics is…
Natural gas at thermodynamic equilibrium Implications for the origin of natural gas
2009-01-01
It is broadly accepted that so-called 'thermal' gas is the product of thermal cracking, 'primary' thermal gas from kerogen cracking, and 'secondary' thermal gas from oil cracking. Since thermal cracking of hydrocarbons does not generate products at equilibrium and thermal stress should not bring them to equilibrium over geologic time, we would not expect methane, ethane, and propane to be at equilibrium in subsurface deposits. Here we report compelling evidence of natural gas at thermodynamic equilibrium. Molecular compositions are constrained to equilibrium, and isotopic compositions are also under equilibrium constraints: The functions [(CH4)*(C3H8)] and [(C2H6)2] exhibit a strong nonlinear correlation (R2 = 0.84) in which the quotient Q progresses to K as wet gas progresses to dry gas. There are striking similarities between natural gas and catalytic gas generated from marine shales. A Devonian/Mississippian New Albany shale generates gas with Q converging on K over time as wet gas progresses to dry gas at 200°C. The position that thermal cracking is the primary source of natural gas is no longer tenable. It is challenged by its inability to explain the composition of natural gas, natural gases at thermodynamic equilibrium, and by the existence of a catalytic path to gas that better explains gas compositions. PMID:19531233
Is Soret equilibrium a non-equilibrium effect?
NASA Astrophysics Data System (ADS)
Würger, Alois
2013-04-01
Recent thermophoretic experiments on colloidal suspensions revived an old debate, namely whether the Soret effect is properly described by thermostatics, or necessarily requires non-equilibrium thermodynamics. Based on colloidal transport theory and the entropy production of the related viscous flow, our analysis leads to the conclusion that the equilibrium approach may work for small ions, yet fails for colloidal particles and polymers. Regarding binary molecular mixtures, our results shed some doubt on the validity of thermostatic approaches that derive the Soret coefficient from equilibrium potentials.
Equilibrium and shot noise in mesoscopic systems
Martin, T.
1994-10-01
Within the last decade, there has been a resurgence of interest in the study of noise in Mesoscopic devices, both experimentally and theoretically. Noise in solid state devices can have different origins: there is 1/f noise, which is believed to arise from fluctuations in the resistance of the sample due to the motion of impurities. On top of this contribution is a frequency independent component associated with the stochastic nature of electron transport, which will be the focus of this paper. If the sample considered is small enough that dephasing and inelastic effects can be neglected, equilibrium (thermal) and excess noise can be completely described in terms of the elastic scattering properties of the sample. As mentioned above, noise arises as a consequence of random processes governing the transport of electrons. Here, there are two sources of randomness: first, electrons incident on the sample occupy a given energy state with a probability given by the Fermi-Dirac distribution function. Secondly, electrons can be transmitted across the sample or reflected in the same reservoir where they came from with a probability given by the quantum mechanical transmission/reflection coefficients. Equilibrium noise refers to the case where no bias voltage is applied between the leads connected to the sample, where thermal agitation alone allows the electrons close to the Fermi level to tunnel through the sample. In general, equilibrium noise is related to the conductance of the sample via the Johnson-Nyquist formula. In the presence of a bias, in the classical regime, one expects to recover the full shot noise < {Delta}{sup 2}I >= 2I{Delta}{mu} as was observed a long time ago in vacuum diodes. In the Mesoscopic regime, however, excess noise is reduced below the shot noise level. The author introduces a more intuitive picture, where the current passing through the device is a superposition of pulses, or electron wave packets, which can be transmitted or reflected.
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.
Womes, M.; Reibel, C.; Mari, A.; Zitoun, D.
2011-04-15
A series of spinel compounds with composition CuFe{sub 0.5}(Sn{sub (1-x)}Ti{sub x}){sub 1.5}S{sub 4} (0{<=}x{<=}1) is analysed by X-ray diffraction, measurements of magnetic susceptibilities and {sup 57}Fe Moessbauer spectroscopy. All samples show a temperature-dependent equilibrium between an electronic low spin 3d(t{sub 2g}){sup 6}(e{sub g}){sup 0} and a high spin 3d(t{sub 2g}){sup 4}(e{sub g}){sup 2} state of the Fe(II) ions. The spin crossover is of the continuous type and extends over several hundred degrees in all samples. The Sn/Ti ratio influences the thermal equilibrium between the two spin states. Substitution of Sn(IV) by the smaller Ti(IV) ions leads to a more compact crystal lattice, which, in contrast to many metal-organic Fe(II) complexes, does not stabilise the low spin state, but increases the residual high spin fraction for T{yields}0 K. The role played by antiferromagnetic spin coupling in the stabilisation of the high spin state is discussed. The results are compared with model calculations treating the effect of magnetic interactions on spin state equilibria. -- Graphical Abstract: Comparison of fractions of high spin Fe(II) from Moessbauer spectra (circles) with plots of {chi}{sub m}T (dots) versus T. Discrepancies between both methods indicate anti-ferromagnetic spin coupling. Display Omitted Research highlights: {yields} Many Fe(II) complexes show thermally induced high spin-low spin crossover. {yields} Spin crossover in spinel compounds is extremely scarce. {yields} Usually, lattice contraction favours the low spin state in Fe(II) complexes. {yields} In these spinels, lattice contraction favours the high spin state. {yields} The stabilisation of the high spin state is explained by spin-spin interactions.
Helical axis stellarator equilibrium model
Koniges, A.E.; Johnson, J.L.
1985-02-01
An asymptotic model is developed to study MHD equilibria in toroidal systems with a helical magnetic axis. Using a characteristic coordinate system based on the vacuum field lines, the equilibrium problem is reduced to a two-dimensional generalized partial differential equation of the Grad-Shafranov type. A stellarator-expansion free-boundary equilibrium code is modified to solve the helical-axis equations. The expansion model is used to predict the equilibrium properties of Asperators NP-3 and NP-4. Numerically determined flux surfaces, magnetic well, transform, and shear are presented. The equilibria show a toroidal Shafranov shift.
Generation of Nitrogen Acceptors in ZnO using Pulse Thermal Processing
Xu, Jun; Ott, Ronald D; Sabau, Adrian S; Pan, Zhengwei; Xiu, Faxian; Liu, Jilin; Erie, Jean-Marie; Norton, David P
2008-01-01
Bipolar doping in wide bandgap semiconductors is difficult to achieve under equilibrium conditions because of the spontaneous formation of compensating defects and unfavorable energetics for dopant substitution. In this work, we explored the use of rapid pulse thermal processing for activating nitrogen dopants into acceptor states in ZnO. Low-temperature photoluminescence spectra revealed both acceptor-bound exciton (A{sup 0}X) and donor-acceptor pair emissions, which present direct evidence for acceptors generated after pulse thermal processing of nitrogen-doped ZnO. This work suggests that pulse thermal processing is potentially an effective method for p-type doping of ZnO.
NASA Astrophysics Data System (ADS)
Esteso, Victoria; Carretero-Palacios, Sol; Míguez, Hernán
2016-04-01
We study at thermal equilibrium the effect of temperature deviations around room temperature on the equilibrium distance (deq) at which thin films made of Teflon, silica, or polystyrene immersed in glycerol levitate over a silicon substrate due to the balance of Casimir, gravity, and buoyancy forces. We find that the equilibrium nature (stable or unstable) of deq is preserved under temperature changes, and provide simple rules to predict whether the new equilibrium position will occur closer to or further from the substrate at the new temperature. These rules depend on the static permittivities of all materials comprised in the system ( ɛ0 ( m ) ) and the equilibrium nature of deq. Our designed dielectric configuration is excellent for experimental observation of thermal effects on the Casimir force indirectly detected through the tunable equilibrium distances (with slab thickness and material properties) in levitation mode.
Equilibrium and Orientation in Cephalopods.
ERIC Educational Resources Information Center
Budelmann, Bernd-Ulrich
1980-01-01
Describes the structure of the equilibrium receptor system in cephalopods, comparing it to the vertebrate counterpart--the vestibular system. Relates the evolution of this complex system to the competition of cephalopods with fishes. (CS)
Equilibrium Constants You Can Smell.
ERIC Educational Resources Information Center
Anderson, Michael; Buckley, Amy
1996-01-01
Presents a simple experiment involving the sense of smell that students can accomplish during a lecture. Illustrates the important concepts of equilibrium along with the acid/base properties of various ions. (JRH)
Equilibrium ignition for ICF capsules
Lackner, K.S.; Colgate, S.A.; Johnson, N.L.; Kirkpatrick, R.C.; Menikoff, R.; Petschek, A.G.
1993-12-31
There are two fundamentally different approaches to igniting DT fuel in an ICF capsule which can be described as equilibrium and hot spot ignition. In both cases, a capsule which can be thought of as a pusher containing the DT fuel is imploded until the fuel reaches ignition conditions. In comparing high-gain ICF targets using cryogenic DT for a pusher with equilibrium ignition targets using high-Z pushers which contain the radiation. The authors point to the intrinsic advantages of the latter. Equilibrium or volume ignition sacrifices high gain for lower losses, lower ignition temperature, lower implosion velocity and lower sensitivity of the more robust capsule to small fluctuations and asymmetries in the drive system. The reduction in gain is about a factor of 2.5, which is small enough to make the more robust equilibrium ignition an attractive alternative.
Edge equilibrium code for tokamaks
Li, Xujing; Drozdov, Vladimir V.
2014-01-15
The edge equilibrium code (EEC) described in this paper is developed for simulations of the near edge plasma using the finite element method. It solves the Grad-Shafranov equation in toroidal coordinate and uses adaptive grids aligned with magnetic field lines. Hermite finite elements are chosen for the numerical scheme. A fast Newton scheme which is the same as implemented in the equilibrium and stability code (ESC) is applied here to adjust the grids.
A search for equilibrium states
NASA Technical Reports Server (NTRS)
Zeleznik, F. J.
1982-01-01
An efficient search algorithm is described for the location of equilibrium states in a search set of states which differ from one another only by the choice of pure phases. The algorithm has three important characteristics: (1) it ignores states which have little prospect for being an improved approximation to the true equilibrium state; (2) it avoids states which lead to singular iteration equations; (3) it furnishes a search history which can provide clues to alternative search paths.
De Vega, H.J.; Boyanovsky, D.
2000-07-17
The Relativistic Heavy Ion Collider (RHIC) at Brookhaven, beginning operation this year, and the Large Hadron Collider (LHC) at CERN, beginning operation {approximately}2005, will provide an unprecedented range of energies and luminosities that will allow us to probe the Gluon-Quark plasma. At RHIC and LHC, at central rapidity typical estimates of energy densities and temperatures are e * 1-10 GeV/fm3 and T0 * 300 - 900 MeV. Such energies are well above current estimates for the GQ plasma. Initially, this hot, dense plasma is far from local thermal equilibrium, making the theoretical study of transport phenomena, kinetic and chemical equilibration in dense and hot plasmas, and related issues a matter of fundamental importance. During the last few years a consistent framework to study collective effects in the Gluon-Quark plasma, and a microscopic description of transport in terms of the hard thermal (and dense) loops resummation program has emerged. This approach has the potential of providing a microscopic formulation of transport, in the regime of temperatures and densities to be achieved at RHIC and LHC. A parallel development over the last few years has provided a consistent formulation of non-equilibrium quantum field theory that provides a real-time description of phenomena out of equilibrium. Novel techniques including non-perturbative approaches and the dynamical renormalization group techniques lead to new insights into transport and relaxation. A deeper understanding of collective.excitations and transport phenomena in the GQ plasma could lead to recognize novel potential experimental signatures. New insights into small-c physics reveals a striking similarity between small-c and hard thermal loops, and novel real-time numerical simulations have recently studied the parton distributions and their thermalizations in the initial stages of a heavy ion collision.
DE VEGA,H.J.; BOYANOVSKY,D.
2000-07-17
The Relativistic Heavy Ion Collider (RHIC) at Brookhaven, beginning operation this year, and the Large Hadron Collider (LHC) at CERN, beginning operation {approximately}2005, will provide an unprecedented range of energies and luminosities that will allow us to probe the Gluon-Quark plasma. At RHIC and LHC, at central rapidity typical estimates of energy densities and temperatures are e * 1-10 GeV/fm3 and T0 * 300 - 900 MeV. Such energies are well above current estimates for the GQ plasma. Initially, this hot, dense plasma is far from local thermal equilibrium, making the theoretical study of transport phenomena, kinetic and chemical equilibration in dense and hot plasmas, and related issues a matter of fundamental importance. During the last few years a consistent framework to study collective effects in the Gluon-Quark plasma, and a microscopic description of transport in terms of the hard thermal (and dense) loops resummation program has emerged. This approach has the potential of providing a microscopic formulation of transport, in the regime of temperatures and densities to be achieved at RHIC and LHC. A parallel development over the last few years has provided a consistent formulation of non-equilibrium quantum field theory that provides a real-time description of phenomena out of equilibrium. Novel techniques including non-perturbative approaches and the dynamical renormalization group techniques lead to new insights into transport and relaxation. A deeper understanding of collective.excitations and transport phenomena in the GQ plasma could lead to recognize novel potential experimental signatures. New insights into small-c physics reveals a striking similarity between small-c and hard thermal loops, and novel real-time numerical simulations have recently studied the parton distributions and their thermalizations in the initial stages of a heavy ion collision.
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
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
Equilibrium and non-equilibrium properties of finite-volume crystallites
NASA Astrophysics Data System (ADS)
Degawa, Masashi
compared with experimental results for Pb crystallites supported on a Ru substrate. The thermodynamic and kinetic parameters are obtained from the observations of equilibrium structures and rates of structure evolution. The predicted dynamic scaling exponents of facet-edge fluctuations are also obtained and compared to an isolated step. Facet-edge fluctuations are also tested with Monte Carlo Simulations (MCS) using the Terrace-Step-Kink (TSK) model with thermally exited kink formations and conserved microscopic processes.
Electron-positron pair equilibrium in strongly magnetized plasmas
Harding, A.K.
1984-11-01
Steady states of thermal electron-positron pair plasmas at mildly relativistic temperatures and in strong magnetic fields are investigated. The pair density in steady-state equilibrium, where pair production balances annihilation, is found as a function of temperature, magnetic field strength and source size, by a numerical calculation which includes pair production attenuation and Compton scattering of the photons. It is found that there is a maximum pair density for each value of temperature and field strength, and also a source size above which optically thin equilibrium states do not exist. (ESA)
Pre-equilibrium approximation in chemical and photophysical kinetics
NASA Astrophysics Data System (ADS)
Rae, Margaret; Berberan-Santos, Mário N.
2002-07-01
For most mechanisms of chemical reactions and molecular photophysical processes the time evolution of the concentration of the intervening species cannot be obtained analytically. The pre-equilibrium approximation is one of several useful approximation methods that allow the derivation of explicit solutions and simplify numerical solutions. In this work, a general view of the pre-equilibrium approximation is presented, along with the respective analytical solution. It is also shown that the kinetic behavior of systems subject to pre-equilibration can be obtained by the application of perturbation theory. Several photophysical systems are discussed, including excimer formation, thermally activated delayed fluorescence, and external-heavy atom quenching of luminescence.
Equilibrium & Nonequilibrium Fluctuation Effects in Biopolymer Networks
NASA Astrophysics Data System (ADS)
Kachan, Devin Michael
Fluctuation-induced interactions are an important organizing principle in a variety of soft matter systems. In this dissertation, I explore the role of both thermal and active fluctuations within cross-linked polymer networks. The systems I study are in large part inspired by the amazing physics found within the cytoskeleton of eukaryotic cells. I first predict and verify the existence of a thermal Casimir force between cross-linkers bound to a semi-flexible polymer. The calculation is complicated by the appearance of second order derivatives in the bending Hamiltonian for such polymers, which requires a careful evaluation of the the path integral formulation of the partition function in order to arrive at the physically correct continuum limit and properly address ultraviolet divergences. I find that cross linkers interact along a filament with an attractive logarithmic potential proportional to thermal energy. The proportionality constant depends on whether and how the cross linkers constrain the relative angle between the two filaments to which they are bound. The interaction has important implications for the synthesis of biopolymer bundles within cells. I model the cross-linkers as existing in two phases: bound to the bundle and free in solution. When the cross-linkers are bound, they behave as a one-dimensional gas of particles interacting with the Casimir force, while the free phase is a simple ideal gas. Demanding equilibrium between the two phases, I find a discontinuous transition between a sparsely and a densely bound bundle. This discontinuous condensation transition induced by the long-ranged nature of the Casimir interaction allows for a similarly abrupt structural transition in semiflexible filament networks between a low cross linker density isotropic phase and a higher cross link density bundle network. This work is supported by the results of finite element Brownian dynamics simulations of semiflexible filaments and transient cross-linkers. I
Equilibrium Model of Precipitation in Microalloyed Steels
NASA Astrophysics Data System (ADS)
Xu, Kun; Thomas, Brian G.; O'Malley, Ron
2011-02-01
The formation of precipitates during thermal processing of microalloyed steels greatly influences their mechanical properties. Precipitation behavior varies with steel composition and temperature history and can lead to beneficial grain refinement or detrimental transverse surface cracks. This work presents an efficient computational model of equilibrium precipitation of oxides, sulfides, nitrides, and carbides in steels, based on satisfying solubility limits including Wagner interaction between elements, mutual solubility between precipitates, and mass conservation of alloying elements. The model predicts the compositions and amounts of stable precipitates for multicomponent microalloyed steels in liquid, ferrite, and austenite phases at any temperature. The model is first validated by comparing with analytical solutions of simple cases, predictions using the commercial package JMat-PRO, and previous experimental observations. Then it is applied to track the evolution of precipitate amounts during continuous casting of two commercial steels (1004 LCAK and 1006Nb HSLA) at two different casting speeds. This model is easy to modify to incorporate other precipitates, or new thermodynamic data, and is a useful tool for equilibrium precipitation analysis.
Diluted equilibrium sterile neutrino dark matter
NASA Astrophysics Data System (ADS)
Patwardhan, Amol V.; Fuller, George M.; Kishimoto, Chad T.; Kusenko, Alexander
2015-11-01
We present a model where sterile neutrinos with rest masses in the range ˜keV to ˜MeV can be the dark matter and be consistent with all laboratory, cosmological, and large-scale structure, as well as x-ray constraints. These sterile neutrinos are assumed to freeze out of thermal and chemical equilibrium with matter and radiation in the very early Universe, prior to an epoch of prodigious entropy generation ("dilution") from out-of-equilibrium decay of heavy particles. In this work, we consider heavy, entropy-producing particles in the ˜TeV to ˜EeV rest-mass range, possibly associated with new physics at high-energy scales. The process of dilution can give the sterile neutrinos the appropriate relic densities, but it also alters their energy spectra so that they could act like cold dark matter, despite relatively low rest masses as compared to conventional dark matter candidates. Moreover, since the model does not rely on active-sterile mixing for producing the relic density, the mixing angles can be small enough to evade current x-ray or lifetime constraints. Nevertheless, we discuss how future x-ray observations, future lepton number constraints, and future observations and sophisticated simulations of large-scale structure could, in conjunction, provide evidence for this model and/or constrain and probe its parameters.
General equilibrium of an ecosystem.
Tschirhart, J
2000-03-01
Ecosystems and economies are inextricably linked: ecosystem models and economic models are not linked. Consequently, using either type of model to design policies for preserving ecosystems or improving economic performance omits important information. Improved policies would follow from a model that links the systems and accounts for the mutual feedbacks by recognizing how key ecosystem variables influence key economic variables, and vice versa. Because general equilibrium economic models already are widely used for policy making, the approach used here is to develop a general equilibrium ecosystem model which captures salient biological functions and which can be integrated with extant economic models. In the ecosystem model, each organism is assumed to be a net energy maximizer that must exert energy to capture biomass from other organisms. The exerted energies are the "prices" that are paid to biomass, and each organism takes the prices as signals over which it has no control. The maximization problem yields the organism's demand for and supply of biomass to other organisms as functions of the prices. The demands and supplies for each biomass are aggregated over all organisms in each species which establishes biomass markets wherein biomass prices are determined. A short-run equilibrium is established when all organisms are maximizing and demand equals supply in every biomass market. If a species exhibits positive (negative) net energy in equilibrium, its population increases (decreases) and a new equilibrium follows. The demand and supply forces in the biomass markets drive each species toward zero stored energy and a long-run equilibrium. Population adjustments are not based on typical Lotka-Volterra differential equations in which one entire population adjusts to another entire population thereby masking organism behavior; instead, individual organism behavior is central to population adjustments. Numerical simulations use a marine food web in Alaska to
Carbon nanotubes as mechanical probes of equilibrium and non-equilibrium cytoskeletal networks
NASA Astrophysics Data System (ADS)
Fakhri, Nikta; Pasquali, Matteo; Mackintosh, Frederick C.; Schmidt, Christoph F.
2012-02-01
Networks of filamentous proteins underlie the mechanics of cells. The activity of motor proteins typically creates strong fluctuations that drive the system out of equilibrium. Understanding the behavior of such networks requires probes that ideally span the characteristic length-scales, from nanometers to micrometers. Single-walled carbon nanotubes (SWNTs) are nanometer-diameter filaments with micrometer length and tunable bending stiffness. On a Brownian energy scale they have persistence lengths of about 20-100 micrometers and show significant thermal fluctuations on the cellular scale of a few microns. Diffusive motion and local bending dynamics of SWNTs embedded in an active polymeric network reflect forces and fluctuations of the embedding medium. We study the motion of individual SWNTs in equilibrium and non-equilibrium networks by near infrared fluorescence microscopy. We show that SWNTs reptate in the network. We will discuss the possibility of using SWNTs as multi-scale probes relating their local dynamic behavior to the viscoelastic properties of the surrounding network.
Adiabatic evolution of plasma equilibrium
Grad, H.; Hu, P. N.; Stevens, D. C.
1975-01-01
A new theory of plasma equilibrium is introduced in which adiabatic constraints are specified. This leads to a mathematically nonstandard structure, as compared to the usual equilibrium theory, in which prescription of pressure and current profiles leads to an elliptic partial differential equation. Topologically complex configurations require further generalization of the concept of adiabaticity to allow irreversible mixing of plasma and magnetic flux among islands. Matching conditions across a boundary layer at the separatrix are obtained from appropriate conservation laws. Applications are made to configurations with planned islands (as in Doublet) and accidental islands (as in Tokamaks). Two-dimensional, axially symmetric, helically symmetric, and closed line equilibria are included. PMID:16578729
Phase coexistence far from equilibrium
NASA Astrophysics Data System (ADS)
Dickman, Ronald
2016-04-01
Investigation of simple far-from-equilibrium systems exhibiting phase separation leads to the conclusion that phase coexistence is not well defined in this context. This is because the properties of the coexisting nonequilibrium systems depend on how they are placed in contact, as verified in the driven lattice gas with attractive interactions, and in the two-temperature lattice gas, under (a) weak global exchange between uniform systems, and (b) phase-separated (nonuniform) systems. Thus, far from equilibrium, the notions of universality of phase coexistence (i.e., independence of how systems exchange particles and/or energy), and of phases with intrinsic properties (independent of their environment) are lost.
Chemical Principles Revisited: Using the Equilibrium Concept.
ERIC Educational Resources Information Center
Mickey, Charles D., Ed.
1981-01-01
Discusses the concept of equilibrium in chemical systems, particularly in relation to predicting the position of equilibrium, predicting spontaneity of a reaction, quantitative applications of the equilibrium constant, heterogeneous equilibrium, determination of the solubility product constant, common-ion effect, and dissolution of precipitates.…
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).
DYNAMIC EQUILIBRIUM IN THERAPEUTIC SITUATIONS.
ERIC Educational Resources Information Center
CARROLL, EDWARD J.
THE CONCEPT OF DYNAMIC EQUILIBRIUM IS USED TO EXAMINE THE OCCURRENCE OF CHANGE IN A THERAPEUTIC INTERVIEW AND TO PROPOSE A THEORY OF THERAPY. BY ANALYZING THE WORKINGS OF THE PSYCHOSOCIAL SYSTEM THROUGH THE GENERAL SYSTEMS THEORY, IT IS POSSIBLE TO SEE HOW CHANGE OCCURS IN AN INDIVIDUAL FAMILY OR COMMUNITY. APPLIED TO A FAMILY INTERVIEW, THE MODEL…
Magnetospheric equilibrium with anisotropic pressure
Cheng, C.Z.
1991-07-01
Self-consistent magnetospheric equilibrium with anisotropic pressure is obtained by employing an iterative metric method for solving the inverse equilibrium equation in an optimal flux coordinate system. A method of determining plasma parallel and perpendicular pressures from either analytic particle distribution or particle distribution measured along the satellite's path is presented. The numerical results of axisymmetric magnetospheric equilibrium including the effects of finite beta, pressure anisotropy, and boundary conditions are presented for a bi-Maxwellian particle distribution. For the isotropic pressure cases, the finite beta effect produces an outward expansion of the constant magnetic flux surfaces in relation to the dipole field lines, and along the magnetic field the toroidal ring current is maximum at the magnetic equator. The effect of pressure anisotropy is found to further expand the flux surfaces outward. Along the magnetic field lines the westward ring current can be peak away from the equator due to an eastward current contribution resulting from pressure anisotropy. As pressure anisotropy increases, the peak westward current can become more singular. The outer boundary flux surface has significant effect on the magnetospheric equilibrium. For the outer flux boundary resembling dayside compressed flux surface due to solar wind pressure, the deformation of the magnetic field can be quite different from that for the outer flux boundary resembling the tail-like surface. 23 refs., 17 figs.
An investigation of equilibrium concepts
NASA Technical Reports Server (NTRS)
Prozan, R. J.
1982-01-01
A different approach to modeling of the thermochemistry of rocket engine combustion phenomena is presented. The methodology described is based on the hypothesis of a new variational principle applicable to compressible fluid mechanics. This hypothesis is extended to treat the thermochemical behavior of a reacting (equilibrium) gas in an open system.
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
Equilibrium spin pulsars unite neutron star populations
NASA Astrophysics Data System (ADS)
Ho, Wynn C. G.; Klus, H.; Coe, M. J.; Andersson, Nils
2014-02-01
Many pulsars are formed with a binary companion from which they can accrete matter. Torque exerted by accreting matter can cause the pulsar spin to increase or decrease, and over long times, an equilibrium spin rate is achieved. Application of accretion theory to these systems provides a probe of the pulsar magnetic field. We compare the large number of recent torque measurements of accreting pulsars with a high-mass companion to the standard model for how accretion affects the pulsar spin period. We find that many long spin period (P ≳ 100 s) pulsars must possess either extremely weak (B < 1010 G) or extremely strong (B > 1014 G) magnetic fields. We argue that the strong-field solution is more compelling, in which case these pulsars are near spin equilibrium. Our results provide evidence for a fundamental link between pulsars with the slowest spin periods and strong magnetic fields around high-mass companions and pulsars with the fastest spin periods and weak fields around low-mass companions. The strong magnetic fields also connect our pulsars to magnetars and strong-field isolated radio/X-ray pulsars. The strong field and old age of our sources suggest their magnetic field penetrates into the superconducting core of the neutron star.
Efficient solution for equilibrium points in transient energy function analysis
Irisarri, G.D.; Ejebe, G.C.; Waight, J.G. ); Tinney, W.F. , Portland, OR )
1994-05-01
A new method for the determination of stable and unstable equilibrium points in the Transient Energy Function method of stability analysis is presented. Computation of the Unstable Equilibrium Point is one of the fundamental steps in determination of the energy margin. The basis of the new method is its formulation as a power flow problem and the use of well known power flow algorithms for its solution. Sparse matrix methods are used to achieve the indicated speedups. The new method has shown robust behavior in all systems tested and performance improvements over previous methods. Results using test systems of up to 161 generators, 901 buses, and 2,000 lines are given.
Radiative-convective equilibrium models of Jupiter and Saturn
NASA Astrophysics Data System (ADS)
Appleby, J. F.; Hogan, J. S.
1984-09-01
Radiative-convective equilibrium models for Jupiter and Saturn have been produced in a study concentrating on the stratospheric energy balance and the possible role of aerosol heating. These models are compared directly with the thermal structure profiles obtained from Voyager radio occultation measurements. The method is based on a straightforward flux divergence formulation derived from earlier work. The balance between absorbed and emitted energies is computed iteratively at each level in the atmosphere, assuming local thermodynamic equilibrium and employing a standard treatment of opacities. Results for Jupiter indicate that a dust-free model furnishes a good mean thermal profile for the stratosphere when compared with the Voyager 1 radio occultation measurements. Observations of the equatorial region exhibit periodic vertical structure. The Saturn models are relatively simple and in good agreement with the Voyager 2 radio occultation temperature profiles at all levels. Aerosol heating played a minor role in Saturn's midlatitude stratospheric energy balance at the time of the Voyager 2 encounter.
A two-dimensional, TVD numerical scheme for inviscid, high Mach number flows in chemical equilibrium
NASA Technical Reports Server (NTRS)
Eberhardt, S.; Palmer, G.
1986-01-01
A new algorithm has been developed for hypervelocity flows in chemical equilibrium. Solutions have been achieved for Mach numbers up to 15 with no adverse effect on convergence. Two methods of coupling an equilibrium chemistry package have been tested, with the simpler method proving to be more robust. Improvements in boundary conditions are still required for a production-quality code.
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.
Conformational equilibrium in supramolecular chemistry: Dibutyltriuret case
Mroczyńska, Karina; Kaczorowska, Małgorzata; Kolehmainen, Erkki; Grubecki, Ireneusz; Pietrzak, Marek
2015-01-01
Summary The association of substituted benzoates and naphthyridine dianions was used to study the complexation of dibutyltriuret. The title molecule is the simplest molecule able to form two intramolecular hydrogen bonds. The naphthyridine salt was used to break two intramolecular hydrogen bonds at a time while with the use of substituted benzoates the systematic approach to study association was achieved. Both, titrations and variable temperature measurements shed the light on the importance of conformational equilibrium and its influence on association in solution. Moreover, the associates were observed by mass spectrometry. The DFT-based computations for complexes and single bond rotational barriers supports experimental data and helps understanding the properties of multiply hydrogen bonded complexes. PMID:26664631
Non-equilibrium Dynamics of DNA Nanotubes
NASA Astrophysics Data System (ADS)
Hariadi, Rizal Fajar
nanotubes with an irreversible energy consumption reaction, analogous to nucleotide hydrolysis in actin and microtubule polymerization. Finally, we integrated the DNA strand displacement circuits with DNA nanotube polymerization to achieve programmable kinetic control of behavior within artificial cytoskeleton. Our synthetic approach may provide insights into natural cytoskeleton dynamics, such as minimal architectural or reaction mechanism requirements for non-equilibrium behaviors including treadmilling and dynamic instability. The outgrowth of DNA nanotechnology beyond its own boundaries, serving as a general model system for biomolecular dynamics, can lead to an understanding of molecular processes that advances both basic and applied sciences.
Kulkarni, Y; Knap, J; Ortiz, M
2007-04-26
The aim of this paper is the development of equilibrium and non-equilibrium extensions of the quasicontinuum (QC) method. We first use variational mean-field theory and the maximum-entropy formalism for deriving approximate probability distribution and partition functions for the system. The resulting probability distribution depends locally on atomic temperatures defined for every atom and the corresponding thermodynamic potentials are explicit and local in nature. The method requires an interatomic potential as the sole empirical input. Numerical validation is performed by simulating thermal equilibrium properties of selected materials using the Lennard-Jones pair potential and the EAM potential and comparing with molecular dynamics results as well as experimental data. The max-ent variational approach is then taken as a basis for developing a three-dimensional non-equilibrium finite temperature extension of the quasicontinuum method. This extension is accomplished by coupling the local temperature-dependent free energy furnished by the max-ent approximation scheme to the heat equation in a joint thermo-mechanical variational setting. Results for finite-temperature nanoindentation tests demonstrate the ability of the method to capture non-equilibrium transport properties and differentiate between slow and fast indentation.
Connective stability of competitive equilibrium
NASA Technical Reports Server (NTRS)
Siljak, D. D.
1975-01-01
The purpose of this paper is to derive necessary and sufficient conditions for the connective stability of nonlinear matrix systems described by the equation x-dot = A(t, x) x, where the matrix A(t, x) has time-varying nonlinear elements. The results obtained can be used to study the stability of competitive equilibrium in fields as diverse as economics and engineering, model ecosystems, and the arms race.-
Punctuated equilibrium comes of age
NASA Astrophysics Data System (ADS)
Gould, Stephan Jay; Eldredge, Niles
1993-11-01
The intense controversies that surrounded the youth of punctuated equilibrium have helped it mature to a useful extension of evolutionary theory. As a complement to phyletic gradualism, its most important implications remain the recognition of stasis as a meaningful and predominant pattern within the history of species, and in the recasting of macroevolution as the differential success of certain species (and their descendants) within clades.
On the electron equilibrium distribution function in the kinetic theory of electron cyclotron maser
NASA Astrophysics Data System (ADS)
Shenggang, Liu
1981-11-01
The problems concerning the specification of electron equilibrium distribution function for the kinetic theory of ECRM are investigated in this paper. After detailed analysis of the published equilibium distribution functions, several conclusion have been achieved.
Thermal Steady States in Fermionic Dissipative Floquet Systems
NASA Astrophysics Data System (ADS)
Seetharam, Karthik; Bardyn, Charles-Edouard; Rudner, Mark; Lindner, Netanel; Refael, Gil
2015-03-01
The possibility to drive quantum systems periodically in time offers unique ways to deeply modify their fundamental properties, as exemplified by Floquet topological insulators. It also opens the door to a variety of non-equilibrium effects. Resonant driving fields, in particular, lead to excitations which can expose the system to heating. Inspired by existing studies of photoexcited semiconductors, we demonstrate that the analog of thermal states can be achieved in a fermionic Floquet system including carrier-carrier interactions, phonon scattering, and spontaneous emission. We show that inelastic ``Floquet-Umklapp'' processes are responsible for non-thermal heating effects, and identify practical conditions under which they are suppressed. We propose to use suitably engineered external reservoirs of carriers to further stabilize thermal features and control the effective chemical potential of the resulting Floquet distributions. Funded by IQIM, NSF, Swiss National Science Foundation, BSF.
Morphodynamic equilibrium of alluvial estuaries
NASA Astrophysics Data System (ADS)
Tambroni, Nicoletta; Bolla Pittaluga, Michele; Canestrelli, Alberto; Lanzoni, Stefano; Seminara, Giovanni
2014-05-01
The evolution of the longitudinal bed profile of an estuary, with given plan-form configuration, subject to given tidal forcing at the mouth and prescribed values of water and sediment supply from the river is investigated numerically. Our main goal is to ascertain whether, starting from some initial condition, the bed evolution tends to reach a unique equilibrium configuration asymptotically in time. Also, we investigate the morphological response of an alluvial estuary to changes in the tidal range and hydrologic forcing (flow and sediment supply). Finally, the solution helps characterizing the transition between the fluvially dominated region and the tidally dominated region of the estuary. All these issues play an important role also in interpreting how the facies changes along the estuary, thus helping to make correct paleo-environmental and sequence-stratigraphic interpretations of sedimentary successions (Dalrymple and Choi, 2007). Results show that the model is able to describe a wide class of settings ranging from tidally dominated estuaries to fluvially dominated estuaries. In the latter case, the solution is found to compare satisfactory with the analytical asymptotic solution recently derived by Seminara et al. (2012), under the hypothesis of fairly 'small' tidal oscillations. Simulations indicate that the system always moves toward an equilibrium configuration in which the net sediment flux in a tidal cycle is constant throughout the estuary and equal to the constant sediment flux discharged from the river. For constant width, the bed equilibrium profile of the estuarine channel is characterized by two distinct regions: a steeper reach seaward, dominated by the tide, and a less steep upstream reach, dominated by the river and characterized by the undisturbed bed slope. Although the latter reach, at equilibrium, is not directly affected by the tidal wave, however starting from an initial uniform stream with the constant 'fluvial' slope, the final
Equilibrium and Stability of Coronal Helmet Streamers
NASA Astrophysics Data System (ADS)
Glukhov, Vyacheslav Sergeevich
1997-05-01
Equilibrium states and stability of partially open magentic field structures in the solar corona are studied. Soft X-ray observations of the birth and evolution of a giant coronal helmet streamer suggest that the energy source responsible for the X-ray manifestation of the structure is most probably located in the lower corona. The downward heat flux is the indication that a significant part of the source's energy is transported to the top of the structure and converted there to a disposable form. It is shown that by applying the thermodynamic equilibrium model of the corona to the two-dimensional X-ray data it is possible to reconstruct the three-dimensional form of the coronal helmet. The general significance of the projective geometry effects for the observation of the solar corona is discussed. The hypothesis of thermal pressure increase as the cause of the observed helmet expansion is verified numerically. It is shown that in the solar corona a relatively small variations of the pressure distribution in the closed field region can cause huge variations in the geometry of a coronal helmet streamer. Numerical simulations of the morphology and energy accumulation in helmet-like structures subject to photospheric shear motion show that the magnetic field surrounding a partially open structure can inhibit catastrophic expansion of the structure as its energy grows. Stability of a coronal streamer in the framework of the neutral current sheet model is studied theoretically. It is shown that effects of viscosity and the finite Larmor radius dominate effects of inertial fluid motion in the tearing mode instability of a neutral current sheet. Two new regimes of the instability are discovered. It is proven that in the solar corona the rates of growth of the neutral current sheet instability are much smaller than previously believed. Implications of the obtained results are discussed.
Experimental studies in non-equilibrium physics
NASA Astrophysics Data System (ADS)
Cressman, John Robert, Jr.
This work is a collection of three experiments aimed at studying different facets of non-equilibrium dynamics. Chapter I concerns strongly compressible turbulence, which turns out to be very different from incompressible turbulence. The focus is on the dispersion of contaminants in such a flow. This type of turbulence can be studied, at very low mach number, by measuring the velocity fields of particles that float on a turbulently stirred body of water. It turns out that in the absence of incompressibility, the turbulence causes particles to cluster rather than to disperse. The implications of the observations are far reaching and include the transport of pollutants on the oceans surface, phytoplankton growth, as well as industrial applications. Chapter II deals with the effects of polymer additives on drag reduction and turbulent suppression, a well-known phenomenon that is not yet understood. In an attempt to simplify the problem, the effects of a polymer additive were investigated in a vortex street formed in a flowing soap film. Measurements suggest that an increase in elongational viscosity is responsible for a substantial reduction in periodic velocity fluctuations. This study also helps to illuminate the mechanism responsible for vortex separation in the wake of a bluff body. Chapter III describes an experiment designed to test a theoretical approach aimed at generalizing the classical fluctuation dissipation theorem (FDT). This theorem applies to systems driven only slightly away from thermal equilibrium, whereas ours, a liquid crystal under-going electroconvection, is so strongly driven, that the FDT does not apply. Both theory and experiment focus on the flux in global power fluctuations. Physical limitations did not permit a direct test of the theory, however it was possible to establish several interesting characteristics of the system: the source of the fluctuations is the transient defect structures that are generated when the system is driven hard
Thermal transport in out-of-equilibrium quantum harmonic chains.
Nicacio, F; Ferraro, A; Imparato, A; Paternostro, M; Semião, F L
2015-04-01
We address the problem of heat transport in a chain of coupled quantum harmonic oscillators, exposed to the influences of local environments of various nature, stressing the effects that the specific nature of the environment has on the phenomenology of the transport process. We study in detail the behavior of thermodynamically relevant quantities such as heat currents and mean energies of the oscillators, establishing rigorous analytical conditions for the existence of a steady state, whose features we analyze carefully. In particular, we assess the conditions that should be faced to recover trends reminiscent of the classical Fourier law of heat conduction and highlight how such a possibility depends on the environment linked to our system. PMID:25974448
Quantum statistical theory of semiconductor junctions in thermal equilibrium
NASA Technical Reports Server (NTRS)
Von Roos, O.
1977-01-01
Free carrier and electric field distributions of one-dimensional semiconductor junctions are evaluated using a quantum mechanical phase-space distribution and its corresponding Boltzmann equation. Attention is given to quantum and exchange corrections in cases of high doping concentrations when carrier densities become degenerate. Quantitative differences between degenerate and classical junction characteristics, e.g., maximum electric field and built-in voltage and carrier concentration within the transition region, are evaluated numerically.
Theory of extrinsic and intrinsic heterojunctions in thermal equilibrium
NASA Technical Reports Server (NTRS)
Von Ross, O.
1980-01-01
A careful analysis of an abrupt heterojunction consisting of two distinct semiconductors either intrinsic or extrinsic is presented. The calculations apply to a one-dimensional, nondegenerate structure. Taking into account all appropriate boundary conditions, it is shown that the intrinsic Fermi level shows a discontinuity at the interface between the two materials which leads to a discontinuity of the valence band edge equal to the difference in the band gap energies of the two materials. The conduction band edge stays continuous however. This result is independent of possible charged interface states and in sharp contrast to the Anderson model. The reasons for this discrepancy are discussed.
Ice ages and the thermal equilibrium of the earth, II
Adam, D.P.
1975-01-01
The energy required to sustain midlatitude continental glaciations comes from solar radiation absorbed by the oceans. It is made available through changes in relative amounts of energy lost from the sea surface as net outgoing infrared radiation, sensible heat loss, and latent heat loss. Ice sheets form in response to the initial occurrence of a large perennial snowfield in the subarctic. When such a snowfield forms, it undergoes a drastic reduction in absorbed solar energy because of its high albedo. When the absorbed solar energy cannot supply local infrared radiation losses, the snowfield cools, thus increasing the energy gradient between itself and external, warmer areas that can act as energy sources. Cooling of the snowfield progresses until the energy gradients between the snowfield and external heat sources are sufficient to bring in enough (latent plus sensible) energy to balance the energy budget over the snowfield. Much of the energy is imported as latent heat. The snow that falls and nourishes the ice sheet is a by-product of the process used to satisfy the energy balance requirements of the snowfield. The oceans are the primary energy source for the ice sheet because only the ocean can supply large amounts of latent heat. At first, some of the energy extracted by the ice sheet from the ocean is stored heat, so the ocean cools. As it cools, less energy is lost as net outgoing infrared radiation, and the energy thus saved is then available to augment evaporation. The ratio between sensible and latent heat lost by the ocean is the Bowen ratio; it depends in part on the sea surface temperature. As the sea surface temperature falls during a glaciation, the Bowen ratio increases, until most of the available energy leaves the oceans as sensible, rather than latent heat. The ice sheet starves, and an interglacial period begins. The oscillations between stadial and interstadial intervals within a glaciation are caused by the effects of varying amounts of glacial meltwater entering the oceans as a surface layer that acts to reduce the amount of energy available for glacial nourishment. This causes the ice sheet to melt back, which continues the supply of meltwater until the ice sheet diminishes to a size consistent with the reduced rate of nourishment. The meltwater supply then decreases, the rate of nourishment increases, and a new stadial begins. ?? 1975.
Adaptive Equilibrium Regulation: A Balancing Act in Two Timescales
Boker, Steven M.
2015-01-01
An equilibrium involves a balancing of forces. Just as one maintains upright posture in standing or walking, many self-regulatory and interpersonal behaviors can be framed as a balancing act between an ever changing environment and within-person processes. The emerging balance between person and environment, the equilibria, are dynamic and adaptive in response to development and learning. A distinction is made between equilibrium achieved solely due to a short timescale balancing of forces and a longer timescale preferred equilibrium which we define as a state towards which the system slowly adapts. Together, these are developed into a framework that this article calls Adaptive Equilibrium Regulation (ÆR), which separates a regulatory process into two timescales: a faster regulation that automatically balances forces and a slower timescale adaptation process that reconfigures the fast regulation so as to move the system towards its preferred equilibrium when an environmental force persists over the longer timescale. This way of thinking leads to novel models for the interplay between multiple timescales of behavior, learning, and development. PMID:27066197
Equilibrium structures in partially ionized rotating plasmas within Hall magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Krishan, V.; Yoshida, Z.
2006-09-01
The formation of equilibrium structures in partially ionized rotating plasmas, consisting of electrons, ions, and neutral molecules, including the Hall effect, is studied in order to diagnose the possible velocity and the magnetic field configurations in a self-consistent manner. A few simple examples show that the linear and the nonlinear force-free magnetic configurations along with essentially nonlinear Beltrami flow field seem to be the general features of plasmas in the special case of the Keplerian rotation relevant for astrophysical plasmas. Thus rotation along with axial bipolar flows emerges as a natural pattern in gravitationally controlled magnetohydrodynamic systems. However, the equilibrium conditions permit more general flow and the magnetic field profiles that can perhaps be fully explored numerically. A special class of equilibria with unit magnetic Prandtl number and equal values of the fractional ion mass density α =ρi/ρn and the Hall parameter ɛ =λi/L exists where ρ's are the uniform mass densities, λi is the ion inertial scale, and L is the scale of the equilibrium structure. An approximate scaling law between the ionization fraction and the scale of the structure is found. Further by expressing the not so well known ionization fraction in terms of the temperature of the system, assuming thermal equilibrium, relationships among the extensive parameters such as the scale, the neutral particle density, the flow velocity, the temperature, and the magnetic field of the equilibrium structure can be determined. There seems to be a good overlap between the Hall and the thermal equilibria. The validity of the neglect of the ion dynamics is discussed.
Torque equilibrium attitude control for Skylab reentry
NASA Technical Reports Server (NTRS)
Glaese, J. R.; Kennel, H. F.
1979-01-01
All the available torque equilibrium attitudes (most were useless from the standpoint of lack of electrical power) and the equilibrium seeking method are presented, as well as the actual successful application during the 3 weeks prior to Skylab reentry.
Graded Achievement, Tested Achievement, and Validity
ERIC Educational Resources Information Center
Brookhart, Susan M.
2015-01-01
Twenty-eight studies of grades, over a century, were reviewed using the argument-based approach to validity suggested by Kane as a theoretical framework. The review draws conclusions about the meaning of graded achievement, its relation to tested achievement, and changes in the construct of graded achievement over time. "Graded…
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.
Mirabilite solubility in equilibrium sea ice brines
NASA Astrophysics Data System (ADS)
Butler, Benjamin Miles; Papadimitriou, Stathys; Santoro, Anna; Kennedy, Hilary
2016-06-01
The sea ice microstructure is permeated by brine channels and pockets that contain concentrated seawater-derived brine. Cooling the sea ice results in further formation of pure ice within these pockets as thermal equilibrium is attained, resulting in a smaller volume of increasingly concentrated residual brine. The coupled changes in temperature and ionic composition result in supersaturation of the brine with respect to mirabilite (Na2SO4·10H2O) at temperatures below -6.38 °C, which consequently precipitates within the sea ice microstructure. Here, mirabilite solubility in natural and synthetic seawater derived brines, representative of sea ice at thermal equilibrium, has been measured in laboratory experiments between 0.2 and -20.6 °C, and hence we present a detailed examination of mirabilite dynamics within the sea ice system. Below -6.38 °C mirabilite displays particularly large changes in solubility as the temperature decreases, and by -20.6 °C its precipitation results in 12.90% and 91.97% reductions in the total dissolved Na+ and SO42- concentrations respectively, compared to that of conservative seawater concentration. Such large non-conservative changes in brine composition could potentially impact upon the measurement of sea ice brine salinity and pH, whilst the altered osmotic conditions may create additional challenges for the sympagic organisms that inhabit the sea ice system. At temperatures above -6.38 °C, mirabilite again displays large changes in solubility that likely aid in impeding its identification in field samples of sea ice. Our solubility measurements display excellent agreement with that of the FREZCHEM model, which was therefore used to supplement our measurements to colder temperatures. Measured and modelled solubility data were incorporated into a 1D model for the growth of first-year Arctic sea ice. Model results ultimately suggest that mirabilite has a near ubiquitous presence in much of the sea ice on Earth, and illustrate the
Gauge Coupling Unification and Nonequilibrium Thermal Dark Matter
NASA Astrophysics Data System (ADS)
Mambrini, Yann; Olive, Keith A.; Quevillon, Jérémie; Zaldívar, Bryan
2013-06-01
We study a new mechanism for the production of dark matter in the Universe which does not rely on thermal equilibrium. Dark matter is populated from the thermal bath subsequent to inflationary reheating via a massive mediator whose mass is above the reheating scale TRH. To this end, we consider models with an extra U(1) gauge symmetry broken at some intermediate scale (Mint≃1010-1012GeV). We show that not only does the model allow for gauge coupling unification (at a higher scale associated with grand unification) but it can provide a dark matter candidate which is a standard model singlet but charged under the extra U(1). The intermediate scale gauge boson(s) which are predicted in several E6/SO(10) constructions can be a natural mediator between dark matter and the thermal bath. We show that the dark matter abundance, while never having achieved thermal equilibrium, is fixed shortly after the reheating epoch by the relation TRH3/Mint4. As a consequence, we show that the unification of gauge couplings which determines Mint also fixes the reheating temperature, which can be as high as TRH≃1011GeV.
Princeton spectral equilibrium code: PSEC
Ling, K.M.; Jardin, S.C.
1984-03-01
A fast computer code has been developed to calculate free-boundary solutions to the plasma equilibrium equation that are consistent with the currents in external coils and conductors. The free-boundary formulation is based on the minimization of a mean-square error epsilon while the fixed-boundary solution is based on a variational principle and spectral representation of the coordinates x(psi,theta) and z(psi,theta). Specific calculations using the Columbia University Torus II, the Poloidal Divertor Experiment (PDX), and the Tokamak Fusion Test Reactor (TFTR) geometries are performed.
Conformations of Proteins in Equilibrium
NASA Astrophysics Data System (ADS)
Micheletti, Cristian; Banavar, Jayanth R.; Maritan, Amos
2001-08-01
We introduce a simple theoretical approach for an equilibrium study of proteins with known native-state structures. We test our approach with results on well-studied globular proteins, chymotrypsin inhibitor (2ci2), barnase, and the alpha spectrin SH3 domain, and present evidence for a hierarchical onset of order on lowering the temperature with significant organization at the local level even at high temperatures. A further application to the folding process of HIV-1 protease shows that the model can be reliably used to identify key folding sites that are responsible for the development of drug resistance.
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.
Remarkable reduction of thermal conductivity in phosphorene phononic crystal
NASA Astrophysics Data System (ADS)
Xu, Wen; Zhang, Gang
2016-05-01
Phosphorene has received much attention due to its interesting physical and chemical properties, and its potential applications such as thermoelectricity. In thermoelectric applications, low thermal conductivity is essential for achieving a high figure of merit. In this work, we propose to reduce the thermal conductivity of phosphorene by adopting the phononic crystal structure, phosphorene nanomesh. With equilibrium molecular dynamics simulations, we find that the thermal conductivity is remarkably reduced in the phononic crystal. Our analysis shows that the reduction is due to the depressed phonon group velocities induced by Brillouin zone folding, and the reduced phonon lifetimes in the phononic crystal. Interestingly, it is found that the anisotropy ratio of thermal conductivity could be tuned by the ‘non-square’ pores in the phononic crystal, as the phonon group velocities in the direction with larger projection of pores is more severely suppressed, leading to greater reduction of thermal conductivity in this direction. Our work provides deep insight into thermal transport in phononic crystals and proposes a new strategy to reduce the thermal conductivity of monolayer phosphorene.
Remarkable reduction of thermal conductivity in phosphorene phononic crystal.
Xu, Wen; Zhang, Gang
2016-05-01
Phosphorene has received much attention due to its interesting physical and chemical properties, and its potential applications such as thermoelectricity. In thermoelectric applications, low thermal conductivity is essential for achieving a high figure of merit. In this work, we propose to reduce the thermal conductivity of phosphorene by adopting the phononic crystal structure, phosphorene nanomesh. With equilibrium molecular dynamics simulations, we find that the thermal conductivity is remarkably reduced in the phononic crystal. Our analysis shows that the reduction is due to the depressed phonon group velocities induced by Brillouin zone folding, and the reduced phonon lifetimes in the phononic crystal. Interestingly, it is found that the anisotropy ratio of thermal conductivity could be tuned by the 'non-square' pores in the phononic crystal, as the phonon group velocities in the direction with larger projection of pores is more severely suppressed, leading to greater reduction of thermal conductivity in this direction. Our work provides deep insight into thermal transport in phononic crystals and proposes a new strategy to reduce the thermal conductivity of monolayer phosphorene. PMID:27033566
NASA Astrophysics Data System (ADS)
Libby, Stephen B.; Harte, Judith A.; Marinak, Michael M.; Zimmerman, George B.; Graziani, Frank R.; Fournier, Kevin B.; More, Richard M.; Kato, Takako; Faussurier, Gerald
2000-10-01
Recently*, we have proposed the idea of treating quasi-steady NLTE phenomena through the computation of the linear response of an LTE plasma to non-Planckian perturbations. This leads to the result that a single redistribution response matrix in radiation group (frequency) space controls all possible small NLTE deviations from a given LTE state. Furthermore, this matrix is shown to obey useful Onsager reciprocity constraints. In this talk, we will describe both recently derived properties of the response matrix, and its application to computing the behaviors of hot dense plasmas. * Libby, S. B. , Graziani, F. R., More, R. M., and Kato, T., in Laser Interaction and Related Plasma Phenomena: 13th International Conference, G. H. Miley and E. M. Campbell . Eds., AIP #CP406, 1997. More, R. M., in Atomic and Molecular Physics of Controlled Thermonuclear Fusion, C. Joachain and D. Post, Eds., Plenum Publishing Corp., pp. 399-440, (1983). Faussurier, G., and More, R.M., JQSRT, 65, 387-391, (2000). More, R.M., and Kato, T. Phys. Rev. Lett., 81 814, (1998).
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
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.
Magnetospheric equilibrium with anisotropic pressure
Cheng, C.Z. )
1992-02-01
Self-consistent magnetospheric equilibria with anisotropic pressure are obtained by employing an iterative metric method for solving the inverse equilibrium equation in an optimal flux coordinate system. A method of determining plasma parallel and perpendicular pressures from either analytic particle distributions or particle distributions measured along a satellite's path is presented. The numerical results of axisymmetric magnetospheric equilibria including the effects of finite beta, pressure anisotropy, and boundary conditions are presented for a bi-Maxwellian particle distribution. For the isotropic pressure cases the finite beta effect produces an outward expansion of the constant magnetic flux surfaces in relation to the dipole field lines, and along the magnetic field the toroidal ring current is maximum at the magnetic equator. The effect of pressure anisotropy is found to further expand the flux surfaces outward. Along the magnetic field lines the westward ring current can be peak away from the equator owing to an eastward current contribution resulting from pressure anisotropy. As pressure anisotropy increases, the peak westward current can become more singular. The outer boundary flux surface has a significant effect on the magnetospheric equilibrium. For the outer flux boundary resembling the dayside compressed flux surface due to solar wind pressure, the deformation of the magnetic field can be quite different from that for the outer flux boundary resembling the taillike flux surface.
Equilibrium Studies of Designed Metalloproteins.
Gibney, B R
2016-01-01
Complete thermodynamic descriptions of the interactions of cofactors with proteins via equilibrium studies are challenging, but are essential to the evaluation of designed metalloproteins. While decades of studies on protein-protein interaction thermodynamics provide a strong underpinning to the successful computational design of novel protein folds and de novo proteins with enzymatic activity, the corresponding paucity of data on metal-protein interaction thermodynamics limits the success of computational metalloprotein design efforts. By evaluating the thermodynamics of metal-protein interactions via equilibrium binding studies, protein unfolding free energy determinations, proton competition equilibria, and electrochemistry, a more robust basis for the computational design of metalloproteins may be provided. Our laboratory has shown that such studies provide detailed insight into the assembly and stability of designed metalloproteins, allow for parsing apart the free energy contributions of metal-ligand interactions from those of porphyrin-protein interactions in hemeproteins, and even reveal their mechanisms of proton-coupled electron transfer. Here, we highlight studies that reveal the complex interplay between the various equilibria that underlie metalloprotein assembly and stability and the utility of making these detailed measurements. PMID:27586343
ERIC Educational Resources Information Center
Silverberg, Lee J.; Raff, Lionel M.
2015-01-01
Thermodynamic spontaneity-equilibrium criteria require that in a single-reaction system, reactions in either the forward or reverse direction at equilibrium be nonspontaneous. Conversely, the concept of dynamic equilibrium holds that forward and reverse reactions both occur at equal rates at equilibrium to the extent allowed by kinetic…
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
Off-equilibrium sphaleron transitions in the Glasma
Mace, Mark; Schlichting, Soren; Venugopalan, Raju
2016-04-28
We perform the first, to our knowledge, classical-statistical real time lattice simulations of topological transitions in the nonequilibrium glasma of weakly coupled but highly occupied gauge fields created immediately after the collision of ultrarelativistic nuclei. Simplifying our description by employing SU(2) gauge fields, and neglecting their longitudinal expansion, we find that the rate of topological transitions is initially strongly enhanced relative to the thermal sphaleron transition rate and decays with time during the thermalization process. Qualitative features of the time dependence of this nonequilibrium transition rate can be understood when expressed in terms of the magnetic screening length, which wemore » also extract nonperturbatively. Furthermore, a detailed investigation of auto-correlation functions of the Chern-Simons number (NCS) reveals non-Markovian features of the evolution distinct from previous simulations of non-Abelian plasmas in thermal equilibrium.« less
Off-equilibrium sphaleron transitions in the glasma
NASA Astrophysics Data System (ADS)
Mace, Mark; Schlichting, Sören; Venugopalan, Raju
2016-04-01
We perform the first, to our knowledge, classical-statistical real time lattice simulations of topological transitions in the nonequilibrium glasma of weakly coupled but highly occupied gauge fields created immediately after the collision of ultrarelativistic nuclei. Simplifying our description by employing SU(2) gauge fields, and neglecting their longitudinal expansion, we find that the rate of topological transitions is initially strongly enhanced relative to the thermal sphaleron transition rate and decays with time during the thermalization process. Qualitative features of the time dependence of this nonequilibrium transition rate can be understood when expressed in terms of the magnetic screening length, which we also extract nonperturbatively. A detailed investigation of autocorrelation functions of the Chern-Simons number (NCS) reveals non-Markovian features of the evolution distinct from previous simulations of non-Abelian plasmas in thermal equilibrium.
Coupling of an average-atom model with a collisional-radiative equilibrium model
Faussurier, G. Blancard, C.; Cossé, P.
2014-11-15
We present a method to combine a collisional-radiative equilibrium model and an average-atom model to calculate bound and free electron wavefunctions in hot dense plasmas by taking into account screening. This approach allows us to calculate electrical resistivity and thermal conductivity as well as pressure in non local thermodynamic equilibrium plasmas. Illustrations of the method are presented for dilute titanium plasma.
Dynamical topological order parameters far from equilibrium
NASA Astrophysics Data System (ADS)
Budich, Jan Carl; Heyl, Markus
2016-02-01
We introduce a topological quantum number—coined dynamical topological order parameter (DTOP)—that is dynamically defined in the real-time evolution of a quantum many-body system and represented by a momentum space winding number of the Pancharatnam geometric phase. Our construction goes conceptually beyond the standard notion of topological invariants characterizing the wave function of a system, which are constants of motion under coherent time evolution. In particular, we show that the DTOP can change its integer value at discrete times where so called dynamical quantum phase transitions occur, thus serving as a dynamical analog of an order parameter. Interestingly, studying quantum quenches in one-dimensional two-banded Bogoliubov-de Gennes models, we find that the DTOP is capable of resolving if the topology of the system Hamiltonian has changed over the quench. Furthermore, we investigate the relation of the DTOP to the dynamics of the string order parameter that characterizes the topology of such systems in thermal equilibrium.
Approach to equilibrium in accelerated global oceanic models
Danabasoglu, G.; McWilliams, J.C.; Large, W.G.
1996-05-01
The approach to equilibrium of a coarse-resolution, seasonally forced, global oceanic general circulation model is investigated, considering the effects of a widely used acceleration technique that distorts the dynamics by using unequal time steps in the governing equations. A measure of the equilibration time for any solution property is defined as the time it takes to go 90% of the way from its present value to its equilibrium value. This measure becomes approximately time invariant only after sufficiently long integration. It indicates that the total kinetic energy and most mass transport rates attain equilibrium within about 90 and 40 calendar years, respectively. The upper-ocean potential temperature and salinity equilibrium times are about 480 and 380 calender years, following 150- and 20-year initial adjustments, respectively. In the abyssal ocean, potential temperature and salinity equilibration take about 4500 and 3900 calender years, respectively. These longer equilibration times are due to the slow diffusion of tracers both along and across the isopycnal surfaces in stably stratified regions, and these times vary with the associated diffusivities. An analysis of synchronous (i.e., not accelerated) integrations shows that there is a complex interplay between convective, advective, and diffusive timescales. Because of the distortion by acceleration of the seasonal cycle, the solutions display some significant adjustments upon switching to synchronous integration. However, the proper seasonal cycle is recovered within five years. Provided that a sufficient equilibrium state has been achieved with acceleration, the model must be integrated synchronously for only about 15 years thereafter to closely approach synchronous equilibrium. 16 refs., 11 figs., 1 tab.
Thermodynamic equilibrium at heterogeneous pressure
NASA Astrophysics Data System (ADS)
Vrijmoed, Johannes C.; Podladchikov, Yuri Y.
2014-05-01
Recent advances in metamorphic petrology point out the importance of grain-scale pressure variations in high-temperature metamorphic rocks. Pressures derived from chemical zonation using unconventional geobarometry based on equal chemical potentials fit mechanically feasible pressure variations. Here a thermodynamic equilibrium method is presented that predicts chemical zoning as a result of pressure variations by Gibbs energy minimization. Equilibrium thermodynamic prediction of the chemical zoning in the case of pressure heterogeneity is done by constraint Gibbs minimization using linear programming techniques. Compositions of phases considered in the calculation are discretized into 'pseudo-compounds' spanning the entire compositional space. Gibbs energies of these discrete compounds are generated for a given range and resolution of pressures for example derived by barometry or from mechanical model predictions. Gibbs energy minimization is subsequently performed considering all compounds of different composition and pressure. In addition to constraining the system composition a certain proportion of the system is constraint at a specified pressure. Input pressure variations need to be discretized and each discrete pressure defines an additional constraint for the minimization. The proportion of the system at each different pressure is equally distributed over the number of input pressures. For example if two input pressures P1 and P2 are specified, two constraints are added: 50 percent of the system is constraint at P1 while the remaining 50 percent is constraint at P2. The method has been tested for a set of 10 input pressures obtained by Tajčmanová et al. (2014) using their unconventional geobarometry method in a plagioclase rim around kyanite. Each input pressure is added as constraint to the minimization (1/10 percent of the system for each discrete pressure). Constraining the system composition to the average composition of the plagioclase rim
Modeling equilibrium Fe isotope fractionation
NASA Astrophysics Data System (ADS)
Anbar, A.; Jarzecki, A.; Spiro, T.
2003-04-01
Research into the stable isotope biogeochemistry of Fe and other transition metals has been driven primarily by analytical innovations which have revealed significant isotope effects in nature and the laboratory. Further development of these new isotope systems requires complementary theoretical research to guide analytical efforts. The results of the first such studies show some discrepancies with experiments. For example, Johnson et al. (2002) report an experimentally-determined 56Fe/54Fe equilibrium fractionation factor between Fe(II) and Fe(III) aquo complexes of ˜1.0025. This effect is ˜50% smaller than predicted theoretically by Schauble et al. (2001). It is important to resolve such discrepancies. Equilibrium isotope fractionation factors can be predicted from vibrational spectroscopic data of isotopically-substituted complexes, or from theoretical predictions of some or all of these frequencies obtained using force field models. The pioneering work of Schauble et al. (2001) utilized a modified Urey-Bradley force field (MUBFF) model. This approach is limiting in at least three ways: First, it is not ab initio, requiring as input some measured vibrational frequencies. Such data are not always available, or may have significant uncertainties. Second, the MUBFF does not include potentially important effects of solvent interaction. Third, because it makes certain assumptions about molecular symmetry, the MUBFF-based approach is not able to model the spectra of mixed-ligand complexes. To address these limitations, we are evaluating the use of density functional theory (DFT) as an ab initio method to predict vibrational frequencies of isotopically-substituted complexes and, hence, equilibrium fractionation factors. In a preliminary examination of the frequency shift upon isotope substitution of the bending and asymmetric stretching modes of the tetrahedral FeCl_42- complex, we find substantial differences between MUBFF and DFT predictions. Results for other Fe
Out of equilibrium: understanding cosmological evolution to lower-entropy states
Aguirre, Anthony; Carroll, Sean M.; Johnson, Matthew C. E-mail: seancarroll@gmail.com
2012-02-01
Despite the importance of the Second Law of Thermodynamics, it is not absolute. Statistical mechanics implies that, given sufficient time, systems near equilibrium will spontaneously fluctuate into lower-entropy states, locally reversing the thermodynamic arrow of time. We study the time development of such fluctuations, especially the very large fluctuations relevant to cosmology. Under fairly general assumptions, the most likely history of a fluctuation out of equilibrium is simply the CPT conjugate of the most likely way a system relaxes back to equilibrium. We use this idea to elucidate the spacetime structure of various fluctuations in (stable and metastable) de Sitter space and thermal anti-de Sitter space.
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 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.
Equilibrium Potentials of Membrane Electrodes
Wang, Jui H.; Copeland, Eva
1973-01-01
A simple thermodynamic theory of the equilibrium potentials of membrane electrodes is formulated and applied to the glass electrode for measurement of pH. The new formulation assumes the selective adsorption or binding of specific ions on the surface of the membrane which may or may not be permeable to the ion, and includes the conventional derivation based on reversible ion transport across membranes as a special case. To test the theory, a platinum wire was coated with a mixture of stearic acid and methyl-tri-n-octyl-ammonium stearate. When this coated electrode was immersed in aqueous phosphate solution, its potential was found to be a linear function of pH from pH 2 to 12 with a slope equal to the theoretical value of 59.0 mV per pH unit at 24°. PMID:4516194
Neoclassical equilibrium in gyrokinetic simulations
Garbet, X.; Dif-Pradalier, G.; Nguyen, C.; Sarazin, Y.; Grandgirard, V.; Ghendrih, Ph.
2009-06-15
This paper presents a set of model collision operators, which reproduce the neoclassical equilibrium and comply with the constraints of a full-f global gyrokinetic code. The assessment of these operators is based on an entropy variational principle, which allows one to perform a fast calculation of the neoclassical diffusivity and poloidal velocity. It is shown that the force balance equation is recovered at lowest order in the expansion parameter, the normalized gyroradius, hence allowing one to calculate correctly the radial electric field. Also, the conventional neoclassical transport and the poloidal velocity are reproduced in the plateau and banana regimes. The advantages and drawbacks of the various model operators are discussed in view of the requirements for neoclassical and turbulent transport.
String fluid in local equilibrium
NASA Astrophysics Data System (ADS)
Schubring, Daniel; Vanchurin, Vitaly
2014-10-01
We study the solutions of string fluid equations under the assumption of a local equilibrium which was previously obtained in the context of the kinetic theory. We show that the fluid can be foliated into noninteracting submanifolds whose equations of motion are exactly that of the wiggly strings considered previously by Vilenkin and Carter. In a special case of negligible statistical variance in either the left- or the right-moving directions of microscopic strings, the submanifolds are described by the action of a null-current-carrying chiral string. When both variances vanish the submanifolds are described by the Nambu-Goto action and the string fluid reduces to the string dust introduced by Stachel.
Local non-equilibrium thermodynamics
Jinwoo, Lee; Tanaka, Hajime
2015-01-01
Local Shannon entropy lies at the heart of modern thermodynamics, with much discussion of trajectory-dependent entropy production. When taken at both boundaries of a process in phase space, it reproduces the second law of thermodynamics over a finite time interval for small scale systems. However, given that entropy is an ensemble property, it has never been clear how one can assign such a quantity locally. Given such a fundamental omission in our knowledge, we construct a new ensemble composed of trajectories reaching an individual microstate, and show that locally defined entropy, information, and free energy are properties of the ensemble, or trajectory-independent true thermodynamic potentials. We find that the Boltzmann-Gibbs distribution and Landauer's principle can be generalized naturally as properties of the ensemble, and that trajectory-free state functions of the ensemble govern the exact mechanism of non-equilibrium relaxation. PMID:25592077
Equilibrium calculations of firework mixtures
Hobbs, M.L.; Tanaka, Katsumi; Iida, Mitsuaki; Matsunaga, Takehiro
1994-12-31
Thermochemical equilibrium calculations have been used to calculate detonation conditions for typical firework components including three report charges, two display charges, and black powder which is used as a fuse or launch charge. Calculations were performed with a modified version of the TIGER code which allows calculations with 900 gaseous and 600 condensed product species at high pressure. The detonation calculations presented in this paper are thought to be the first report on the theoretical study of firework detonation. Measured velocities for two report charges are available and compare favorably to predicted detonation velocities. However, the measured velocities may not be true detonation velocities. Fast deflagration rather than an ideal detonation occurs when reactants contain significant amounts of slow reacting constituents such as aluminum or titanium. Despite such uncertainties in reacting pyrotechnics, the detonation calculations do show the complex nature of condensed phase formation at elevated pressures and give an upper bound for measured velocities.
Local non-equilibrium thermodynamics.
Jinwoo, Lee; Tanaka, Hajime
2015-01-01
Local Shannon entropy lies at the heart of modern thermodynamics, with much discussion of trajectory-dependent entropy production. When taken at both boundaries of a process in phase space, it reproduces the second law of thermodynamics over a finite time interval for small scale systems. However, given that entropy is an ensemble property, it has never been clear how one can assign such a quantity locally. Given such a fundamental omission in our knowledge, we construct a new ensemble composed of trajectories reaching an individual microstate, and show that locally defined entropy, information, and free energy are properties of the ensemble, or trajectory-independent true thermodynamic potentials. We find that the Boltzmann-Gibbs distribution and Landauer's principle can be generalized naturally as properties of the ensemble, and that trajectory-free state functions of the ensemble govern the exact mechanism of non-equilibrium relaxation. PMID:25592077
Hierarchical condensation near phase equilibrium
NASA Astrophysics Data System (ADS)
Olemskoi, A. I.; Yushchenko, O. V.; Borisyuk, V. N.; Zhilenko, T. I.; Kosminska, Yu. O.; Perekrestov, V. I.
2012-06-01
A novel mechanism of new phase formation is studied both experimentally and theoretically in the example of quasi-equilibrium stationary condensation in an ion-plasma sputterer. Copper condensates are obtained to demonstrate that a specific network structure is formed as a result of self-assembly in the course of deposition. The fractal pattern related is inherent in the phenomena of diffusion limited aggregation. Condensate nuclei are shown to form statistical ensemble of hierarchically subordinated objects distributed in ultrametric space. The Langevin equation and the Fokker-Planck equation related are found to describe stationary distribution of thermodynamic potential variations at condensation. Time dependence of the formation probability of branching structures is found to clarify the experimental situation.
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.
The equilibrium structure of thin magnetic flux tubes. I
NASA Technical Reports Server (NTRS)
Ferrari, A.; Massaglia, S.; Kalkofen, W.; Rosner, R.; Bodo, G.
1985-01-01
A model atmosphere within a thin magnetic flux tube that is embedded in an arbitrarily stratified medium is presently constructed by solving the radiative transfer equation in the two-stream approximation for gray opacity, under the assumption that the magnetic field is sufficiently strong to warrant the neglect of both thermal conduction and convective diffusion; energy inside the flux tube therefore being transported solely by radiation. The structure of the internal atmosphere is determined on the basis of the hydrostatic and radiative equilibrium conditions of the tube embedded in an external atmosphere. The gas temperature along the axis of the tube is computed, and the geometry of the flux tube is determined on the basis of magnetic flux conservation and total pressure equilibrium.
NASA Astrophysics Data System (ADS)
Laurati, Marco; Capellmann, Ronja; Kohl, Matthias; Egelhaaf, Stefan; Schmiedeberg, Michael
The macroscopic properties of gels arise from their slow dynamics and load bearing network structure, which are exploited by nature and in numerous industrial products. However, a link between these structural and dynamical properties has remained elusive. Here we present confocal microscopy exper- iments and simulations of gel-forming colloid-polymer mixtures with competing interactions. They reveal that gel formation is preceded by continuous and directed percolation. Both transitions lead to system spanning networks, but only directed percolation results in extremely slow dynamics, ageing and a shrinking of the gel that resembles syneresis. Therefore, dynamical arrest in gels is found to be linked to a structural transition, namely directed percolation, which is quantitatively associated with the mean number of bonded neighbours. Directed percolation is a universality class of transitions out of equilibrium, our study hence connects gel formation to a well-developed theoretical framework which now can be exploited to achieve a detailed understanding of arrested gels.
Thermalization of Bipartite Bose-Hubbard Models.
Khripkov, Christine; Cohen, Doron; Vardi, Amichay
2016-05-19
We study the time evolution of a bipartite Bose-Hubbard model prepared far from equilibrium. When the classical dynamics is chaotic, we observe ergodization of the number distribution and a constant increase of the entanglement entropy between the constituent subsystems until it saturates to thermal equilibrium values. No thermalization is obtained when the system is launched in quasi-integrable phase space regions. PMID:26701599
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.
Robustly Engineering Thermal Conductivity of Bilayer Graphene by Interlayer Bonding
NASA Astrophysics Data System (ADS)
Zhang, Xiaoliang; Gao, Yufei; Chen, Yuli; Hu, Ming
2016-02-01
Graphene and its bilayer structure are the two-dimensional crystalline form of carbon, whose extraordinary electron mobility and other unique features hold great promise for nanoscale electronics and photonics. Their realistic applications in emerging nanoelectronics usually call for thermal transport manipulation in a controllable and precise manner. In this paper we systematically studied the effect of interlayer covalent bonding, in particular different interlay bonding arrangement, on the thermal conductivity of bilayer graphene using equilibrium molecular dynamics simulations. It is revealed that, the thermal conductivity of randomly bonded bilayer graphene decreases monotonically with the increase of interlayer bonding density, however, for the regularly bonded bilayer graphene structure the thermal conductivity possesses unexpectedly non-monotonic dependence on the interlayer bonding density. The results suggest that the thermal conductivity of bilayer graphene depends not only on the interlayer bonding density, but also on the detailed topological configuration of the interlayer bonding. The underlying mechanism for this abnormal phenomenon is identified by means of phonon spectral energy density, participation ratio and mode weight factor analysis. The large tunability of thermal conductivity of bilayer graphene through rational interlayer bonding arrangement paves the way to achieve other desired properties for potential nanoelectronics applications involving graphene layers.
Robustly Engineering Thermal Conductivity of Bilayer Graphene by Interlayer Bonding
Zhang, Xiaoliang; Gao, Yufei; Chen, Yuli; Hu, Ming
2016-01-01
Graphene and its bilayer structure are the two-dimensional crystalline form of carbon, whose extraordinary electron mobility and other unique features hold great promise for nanoscale electronics and photonics. Their realistic applications in emerging nanoelectronics usually call for thermal transport manipulation in a controllable and precise manner. In this paper we systematically studied the effect of interlayer covalent bonding, in particular different interlay bonding arrangement, on the thermal conductivity of bilayer graphene using equilibrium molecular dynamics simulations. It is revealed that, the thermal conductivity of randomly bonded bilayer graphene decreases monotonically with the increase of interlayer bonding density, however, for the regularly bonded bilayer graphene structure the thermal conductivity possesses unexpectedly non-monotonic dependence on the interlayer bonding density. The results suggest that the thermal conductivity of bilayer graphene depends not only on the interlayer bonding density, but also on the detailed topological configuration of the interlayer bonding. The underlying mechanism for this abnormal phenomenon is identified by means of phonon spectral energy density, participation ratio and mode weight factor analysis. The large tunability of thermal conductivity of bilayer graphene through rational interlayer bonding arrangement paves the way to achieve other desired properties for potential nanoelectronics applications involving graphene layers. PMID:26911859
Mathematical modeling of non-equilibrium sorption
NASA Astrophysics Data System (ADS)
Kaliev, Ibragim A.; Mukhambetzhanov, Saltanbek T.; Sabitova, Gulnara S.; Sakhit, Anghyz E.
2016-08-01
We consider the system of equations modeling the process of non-equilibrium sorption. Difference approximation of differential problem by the implicit scheme is formulated. The solution of the difference problem is constructed using the sweep method. Based on the numerical results we can conclude the following: when the relaxation time decreases to 0, then the solution of non-equilibrium problem tends with increasing time to solution of the equilibrium problem.
Philicities, Fugalities, and Equilibrium Constants.
Mayr, Herbert; Ofial, Armin R
2016-05-17
The mechanistic model of Organic Chemistry is based on relationships between rate and equilibrium constants. Thus, strong bases are generally considered to be good nucleophiles and poor nucleofuges. Exceptions to this rule have long been known, and the ability of iodide ions to catalyze nucleophilic substitutions, because they are good nucleophiles as well as good nucleofuges, is just a prominent example for exceptions from the general rule. In a reaction series, the Leffler-Hammond parameter α = δΔG(⧧)/δΔG° describes the fraction of the change in the Gibbs energy of reaction, which is reflected in the change of the Gibbs energy of activation. It has long been considered as a measure for the position of the transition state; thus, an α value close to 0 was associated with an early transition state, while an α value close to 1 was considered to be indicative of a late transition state. Bordwell's observation in 1969 that substituent variation in phenylnitromethanes has a larger effect on the rates of deprotonation than on the corresponding equilibrium constants (nitroalkane anomaly) triggered the breakdown of this interpretation. In the past, most systematic investigations of the relationships between rates and equilibria of organic reactions have dealt with proton transfer reactions, because only for few other reaction series complementary kinetic and thermodynamic data have been available. In this Account we report on a more general investigation of the relationships between Lewis basicities, nucleophilicities, and nucleofugalities as well as between Lewis acidities, electrophilicities, and electrofugalities. Definitions of these terms are summarized, and it is suggested to replace the hybrid terms "kinetic basicity" and "kinetic acidity" by "protophilicity" and "protofugality", respectively; in this way, the terms "acidity" and "basicity" are exclusively assigned to thermodynamic properties, while "philicity" and "fugality" refer to kinetics
Equilibrium Control Policies for Markov Chains
Malikopoulos, Andreas
2011-01-01
The average cost criterion has held great intuitive appeal and has attracted considerable attention. It is widely employed when controlling dynamic systems that evolve stochastically over time by means of formulating an optimization problem to achieve long-term goals efficiently. The average cost criterion is especially appealing when the decision-making process is long compared to other timescales involved, and there is no compelling motivation to select short-term optimization. This paper addresses the problem of controlling a Markov chain so as to minimize the average cost per unit time. Our approach treats the problem as a dual constrained optimization problem. We derive conditions guaranteeing that a saddle point exists for the new dual problem and we show that this saddle point is an equilibrium control policy for each state of the Markov chain. For practical situations with constraints consistent to those we study here, our results imply that recognition of such saddle points may be of value in deriving in real time an optimal control policy.
Equilibrium sampling by reweighting nonequilibrium simulation trajectories
NASA Astrophysics Data System (ADS)
Yang, Cheng; Wan, Biao; Xu, Shun; Wang, Yanting; Zhou, Xin
2016-03-01
Based on equilibrium molecular simulations, it is usually difficult to efficiently visit the whole conformational space of complex systems, which are separated into some metastable regions by high free energy barriers. Nonequilibrium simulations could enhance transitions among these metastable regions and then be applied to sample equilibrium distributions in complex systems, since the associated nonequilibrium effects can be removed by employing the Jarzynski equality (JE). Here we present such a systematical method, named reweighted nonequilibrium ensemble dynamics (RNED), to efficiently sample equilibrium conformations. The RNED is a combination of the JE and our previous reweighted ensemble dynamics (RED) method. The original JE reproduces equilibrium from lots of nonequilibrium trajectories but requires that the initial distribution of these trajectories is equilibrium. The RED reweights many equilibrium trajectories from an arbitrary initial distribution to get the equilibrium distribution, whereas the RNED has both advantages of the two methods, reproducing equilibrium from lots of nonequilibrium simulation trajectories with an arbitrary initial conformational distribution. We illustrated the application of the RNED in a toy model and in a Lennard-Jones fluid to detect its liquid-solid phase coexistence. The results indicate that the RNED sufficiently extends the application of both the original JE and the RED in equilibrium sampling of complex systems.
Equilibrium sampling by reweighting nonequilibrium simulation trajectories.
Yang, Cheng; Wan, Biao; Xu, Shun; Wang, Yanting; Zhou, Xin
2016-03-01
Based on equilibrium molecular simulations, it is usually difficult to efficiently visit the whole conformational space of complex systems, which are separated into some metastable regions by high free energy barriers. Nonequilibrium simulations could enhance transitions among these metastable regions and then be applied to sample equilibrium distributions in complex systems, since the associated nonequilibrium effects can be removed by employing the Jarzynski equality (JE). Here we present such a systematical method, named reweighted nonequilibrium ensemble dynamics (RNED), to efficiently sample equilibrium conformations. The RNED is a combination of the JE and our previous reweighted ensemble dynamics (RED) method. The original JE reproduces equilibrium from lots of nonequilibrium trajectories but requires that the initial distribution of these trajectories is equilibrium. The RED reweights many equilibrium trajectories from an arbitrary initial distribution to get the equilibrium distribution, whereas the RNED has both advantages of the two methods, reproducing equilibrium from lots of nonequilibrium simulation trajectories with an arbitrary initial conformational distribution. We illustrated the application of the RNED in a toy model and in a Lennard-Jones fluid to detect its liquid-solid phase coexistence. The results indicate that the RNED sufficiently extends the application of both the original JE and the RED in equilibrium sampling of complex systems. PMID:27078486
Determining Equilibrium Position For Acoustical Levitation
NASA Technical Reports Server (NTRS)
Barmatz, M. B.; Aveni, G.; Putterman, S.; Rudnick, J.
1989-01-01
Equilibrium position and orientation of acoustically-levitated weightless object determined by calibration technique on Earth. From calibration data, possible to calculate equilibrium position and orientation in presence of Earth gravitation. Sample not levitated acoustically during calibration. Technique relies on Boltzmann-Ehrenfest adiabatic-invariance principle. One converts resonant-frequency-shift data into data on normalized acoustical potential energy. Minimum of energy occurs at equilibrium point. From gradients of acoustical potential energy, one calculates acoustical restoring force or torque on objects as function of deviation from equilibrium position or orientation.
1-D EQUILIBRIUM DISCRETE DIFFUSION MONTE CARLO
T. EVANS; ET AL
2000-08-01
We present a new hybrid Monte Carlo method for 1-D equilibrium diffusion problems in which the radiation field coexists with matter in local thermodynamic equilibrium. This method, the Equilibrium Discrete Diffusion Monte Carlo (EqDDMC) method, combines Monte Carlo particles with spatially discrete diffusion solutions. We verify the EqDDMC method with computational results from three slab problems. The EqDDMC method represents an incremental step toward applying this hybrid methodology to non-equilibrium diffusion, where it could be simultaneously coupled to Monte Carlo transport.
EASI - EQUILIBRIUM AIR SHOCK INTERFERENCE
NASA Technical Reports Server (NTRS)
Glass, C. E.
1994-01-01
New research on hypersonic vehicles, such as the National Aero-Space Plane (NASP), has raised concerns about the effects of shock-wave interference on various structural components of the craft. State-of-the-art aerothermal analysis software is inadequate to predict local flow and heat flux in areas of extremely high heat transfer, such as the surface impingement of an Edney-type supersonic jet. EASI revives and updates older computational methods for calculating inviscid flow field and maximum heating from shock wave interference. The program expands these methods to solve problems involving the six shock-wave interference patterns on a two-dimensional cylindrical leading edge with an equilibrium chemically reacting gas mixture (representing, for example, the scramjet cowl of the NASP). The inclusion of gas chemistry allows for a more accurate prediction of the maximum pressure and heating loads by accounting for the effects of high temperature on the air mixture. Caloric imperfections and specie dissociation of high-temperature air cause shock-wave angles, flow deflection angles, and thermodynamic properties to differ from those calculated by a calorically perfect gas model. EASI contains pressure- and temperature-dependent thermodynamic and transport properties to determine heating rates, and uses either a calorically perfect air model or an 11-specie, 7-reaction reacting air model at equilibrium with temperatures up to 15,000 K for the inviscid flowfield calculations. EASI solves the flow field and the associated maximum surface pressure and heat flux for the six common types of shock wave interference. Depending on the type of interference, the program solves for shock-wave/boundary-layer interaction, expansion-fan/boundary-layer interaction, attaching shear layer or supersonic jet impingement. Heat flux predictions require a knowledge (from experimental data or relevant calculations) of a pertinent length scale of the interaction. Output files contain flow
Equilibrium coexistence of three amphiboles
Robinson, P.; Jaffe, H.W.; Klein, C., Jr.; Ross, M.
1969-01-01
Electron probe and wet chemical analyses of amphibole pairs from the sillimanite zone of central Massachusetts and adjacent New Hampshire indicated that for a particular metamorphic grade there should be a restricted composition range in which three amphiboles can coexist stably. An unequivocal example of such an equilibrium three amphibole rock has been found in the sillimanite-orthoclase zone. It contains a colorless primitive clinoamphibole, space group P21/m, optically and chemically like cummingtonite with blue-green hornblende exsolution lamellae on (100) and (-101) of the host; blue-green hornblende, space group C2/m, with primitive cummingtonite exsolution lamellae on (100) and (-101) of the host; and pale pinkish tan anthophyllite, space group Pnma, that is free of visible exsolution lamellae but is a submicroscopic intergrowth of two orthorhombic amphiboles. Mutual contacts and coarse, oriented intergrowths of two and three host amphiboles indicate the three grew as an equilibrium assemblage prior to exsolution. Electron probe analyses at mutual three-amphibole contacts showed little variation in the composition of each amphibole. Analyses believed to represent most closely the primary amphibole compositions gave atomic proportions on the basis of 23 oxygens per formula unit as follows: for primitive cummingtonite (Na0.02Ca0.21- Mn0.06Fe2+2.28Mg4.12Al0.28) (Al0.17Si7.83), for hornblende (Na0.35Ca1.56Mn0.02Fe1.71Mg2.85Al0.92) (Al1.37Si6.63), and for anthophyllite (Na0.10Ca0.06Mn0.06Fe2.25Mg4.11Al0.47) (Al0.47Si7.53). The reflections violating C-symmetry, on X-ray single crystal photographs of the primitive cummingtonite, are weak and diffuse, and suggest a partial inversion from a C-centered to a primitive clinoamphibole. Single crystal photographs of the anthophyllite show split reflections indicating it is an intergrowth of about 80% anthophyllite and about 20% gedrite which differ in their b crystallographic dimensions. Split reflections are
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.
Coppola, C. M.; Longo, S.; D'Introno, R.; Galli, D.; Tennyson, J.
2012-03-01
Energy exchange processes play a crucial role in the early universe, affecting the thermal balance and the dynamical evolution of the primordial gas. In the present work we focus on the consequences of a non-thermal distribution of the level populations of H{sub 2}: first, we determine the excitation temperatures of vibrational transitions and the non-equilibrium heat transfer; second, we compare the modifications to chemical reaction rate coefficients with respect to the values obtained assuming local thermodynamic equilibrium; and third, we compute the spectral distortions to the cosmic background radiation generated by the formation of H{sub 2} in vibrationally excited levels. We conclude that non-equilibrium processes cannot be ignored in cosmological simulations of the evolution of baryons, although their observational signatures remain below current limits of detection. New fits to the equilibrium and non-equilibrium heat transfer functions are provided.
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.
Non-equilibrium steady state in the hydro regime
NASA Astrophysics Data System (ADS)
Pourhasan, Razieh
2016-02-01
We study the existence and properties of the non-equilibrium steady state which arises by putting two copies of systems at different temperatures into a thermal contact. We solve the problem for the relativistic systems that are described by the energy-momentum of a perfect hydro with general equation of state (EOS). In particular, we examine several simple examples: a hydro with a linear EOS, a holographic CFT perturbed by a relevant operator and a barotropic fluid, i.e., P=P({E}) . Our studies suggest that the formation of steady state is a universal result of the hydro regime regardless of the kind of fluid.
Ringed Accretion Disks: Equilibrium Configurations
NASA Astrophysics Data System (ADS)
Pugliese, D.; Stuchlík, Z.
2015-12-01
We investigate a model of a ringed accretion disk, made up by several rings rotating around a supermassive Kerr black hole attractor. Each toroid of the ringed disk is governed by the general relativity hydrodynamic Boyer condition of equilibrium configurations of rotating perfect fluids. Properties of the tori can then be determined by an appropriately defined effective potential reflecting the background Kerr geometry and the centrifugal effects. The ringed disks could be created in various regimes during the evolution of matter configurations around supermassive black holes. Therefore, both corotating and counterrotating rings have to be considered as being a constituent of the ringed disk. We provide constraints on the model parameters for the existence and stability of various ringed configurations and discuss occurrence of accretion onto the Kerr black hole and possible launching of jets from the ringed disk. We demonstrate that various ringed disks can be characterized by a maximum number of rings. We present also a perturbation analysis based on evolution of the oscillating components of the ringed disk. The dynamics of the unstable phases of the ringed disk evolution seems to be promising in relation to high-energy phenomena demonstrated in active galactic nuclei.
Deterministic nonclassicality for quantum-mechanical oscillators in thermal states
NASA Astrophysics Data System (ADS)
Marek, Petr; Lachman, Lukáš; Slodička, Lukáš; Filip, Radim
2016-07-01
Quantum nonclassicality is the basic building stone for the vast majority of quantum information applications and methods of its generation are at the forefront of research. One of the obstacles any method needs to clear is the looming presence of decoherence and noise which act against the nonclassicality and often erase it completely. In this paper we show that nonclassical states of a quantum harmonic oscillator initially in thermal equilibrium states can be deterministically created by coupling it to a single two-level system. This can be achieved even in the absorption regime in which the two-level system is initially in the ground state. The method is resilient to noise and it may actually benefit from it, as witnessed by the systems with higher thermal energy producing more nonclassical states.
Colloquium: Homochirality: Symmetry breaking in systems driven far from equilibrium
NASA Astrophysics Data System (ADS)
Saito, Yukio; Hyuga, Hiroyuki
2013-04-01
Subsequent to the discovery of chirality of organic molecules by Pasteur, living organisms have been found to utilize biomolecules of only one handedness. The origin of this homochirality in life still remains unknown. It is believed that homochirality is attained in two stages: the initial creation of a chirality bias and its subsequent amplification to pure chirality. In the last two decades, two novel experiments have established the second stage in different fields: Soai and co-workers achieved the amplification of enantiomeric excess in the production of chiral organic molecules, and Viedma obtained homochirality in the solution growth of sodium chlorate crystals. These experiments are explained by a theory with a nonlinear evolution equation for the chiral order parameter; nonlinear processes in reactions or in crystal growth induce enantiomeric excess amplification, and the recycling of achiral elements ensures homochirality. Recycling drives the system to a state far from equilibrium with a free energy higher than that of the equilibrium state.
Loop Electrostatics Asymmetry Modulates the Preexisting Conformational Equilibrium in Thrombin.
Pozzi, Nicola; Zerbetto, Mirco; Acquasaliente, Laura; Tescari, Simone; Frezzato, Diego; Polimeno, Antonino; Gohara, David W; Di Cera, Enrico; De Filippis, Vincenzo
2016-07-19
Thrombin exists as an ensemble of active (E) and inactive (E*) conformations that differ in their accessibility to the active site. Here we show that redistribution of the E*-E equilibrium can be achieved by perturbing the electrostatic properties of the enzyme. Removal of the negative charge of the catalytic Asp102 or Asp189 in the primary specificity site destabilizes the E form and causes a shift in the 215-217 segment that compromises substrate entrance. Solution studies and existing structures of D102N document stabilization of the E* form. A new high-resolution structure of D189A also reveals the mutant in the collapsed E* form. These findings establish a new paradigm for the control of the E*-E equilibrium in the trypsin fold. PMID:27347732
Punctuated equilibrium and power law in economic dynamics
NASA Astrophysics Data System (ADS)
Gupta, Abhijit Kar
2012-02-01
This work is primarily based on a recently proposed toy model by Thurner et al. (2010) [3] on Schumpeterian economic dynamics (inspired by the idea of economist Joseph Schumpeter [9]). Interestingly, punctuated equilibrium has been shown to emerge from the dynamics. The punctuated equilibrium and Power law are known to be associated with similar kinds of biologically relevant evolutionary models proposed in the past. The occurrence of the Power law is a signature of Self-Organised Criticality (SOC). In our view, power laws can be obtained by controlling the dynamics through incorporating the idea of feedback into the algorithm in some way. The so-called 'feedback' was achieved by introducing the idea of fitness and selection processes in the biological evolutionary models. Therefore, we examine the possible emergence of a power law by invoking the concepts of 'fitness' and 'selection' in the present model of economic evolution.
Testing Hardy-Weinberg equilibrium: an objective Bayesian analysis.
Consonni, Guido; Moreno, Elías; Venturini, Sergio
2011-01-15
We analyze the general (multiallelic) Hardy-Weinberg equilibrium problem from an objective Bayesian testing standpoint. We argue that for small or moderate sample sizes the answer is rather sensitive to the prior chosen, and this suggests to carry out a sensitivity analysis with respect to the prior. This goal is achieved through the identification of a class of priors specifically designed for this testing problem. In this paper, we consider the class of intrinsic priors under the full model, indexed by a tuning quantity, the training sample size. These priors are objective, satisfy Savage's continuity condition and have proved to behave extremely well for many statistical testing problems. We compute the posterior probability of the Hardy-Weinberg equilibrium model for the class of intrinsic priors, assess robustness over the range of plausible answers, as well as stability of the decision in favor of either hypothesis. PMID:20963736
Equilibrium Tail Distribution Due to Touschek Scattering
Nash,B.; Krinsky, S.
2009-05-04
Single large angle Coulomb scattering is referred to as Touschek scattering. In addition to causing particle loss when the scattered particles are outside the momentum aperture, the process also results in a non-Gaussian tail, which is an equilibrium between the Touschek scattering and radiation damping. Here we present an analytical calculation for this equilibrium distribution.
A Holistic Equilibrium Theory of Organization Development
ERIC Educational Resources Information Center
Yang, Baiyin; Zheng, Wei
2005-01-01
This paper proposes a holistic equilibrium theory of organizational development (OD). The theory states that there are three driving forces in organizational change and development--rationality, reality, and liberty. OD can be viewed as a planned process of change in an organization so as to establish equilibrium among these three interacting…
Equilibrium figures in geodesy and geophysics.
NASA Astrophysics Data System (ADS)
Moritz, H.
There is an enormous literature on geodetic equilibrium figures, but the various works have not always been interrelated, also for linguistic reasons (English, French, German, Italian, Russian). The author attempts to systematize the various approaches and to use the standard second-order theory for a study of the deviation of the actual earth and of the equipotential reference ellipsoid from an equilibrium figure.
ERIC Educational Resources Information Center
Ghirardi, Marco; Marchetti, Fabio; Pettinari, Claudio; Regis, Alberto; Roletto, Ezio
2015-01-01
A didactic sequence is proposed for the teaching of chemical equilibrium law. In this approach, we have avoided the kinetic derivation and the thermodynamic justification of the equilibrium constant. The equilibrium constant expression is established empirically by a trial-and-error approach. Additionally, students learn to use the criterion of…
Equilibrium thermophysical properties of alkanes at very high temperatures
Arunachalam, C.; Bozkurt, B.; Eubank, P.T.
1996-01-01
In order to perform calculations for thermal plasmas, sparks, and arcs, as in the thermal arc and electrical discharge machining (EDM) processes, thermophysical properties, such as the density, enthalpy, and heat capacity, of the original ambient dielectric liquid are required at very high temperatures and often pressures in the plasma state. A statistical model has been developed to provide these properties. At high temperatures, these hydrocarbons undergo a series of reactions to first dissociate and then to ionize to produce a plasma. The partition functions of each of the species generated are calculated and sued to determine the equilibrium mole fractions or particle fractions of each constituent of the resultant plasma. Only the hydrogen-to-carbon ratio matters so mixtures of alkanes can also be used. Specifically, tables of particles fractions, densities, enthalpies, and specific heat capacities are provided for methane and for hexadecane to 60,000 K and 10 kbar.
Cavity Dephasing in Transmon Qubits from Non-equilibrium Noise
NASA Astrophysics Data System (ADS)
Yeh, Jen-Hao; Lefebvre, Jay; Wellstood, Frederick; Palmer, Benjamin
The dephasing times for transmon qubits in a 3D cavity can be limited by coupling of the cavity input and output lines to non-equilibrium noise from higher temperature stages. In our system, the dominant source of thermal photons in the cavity is the last microwave attenuator in the microwave input line which is mounted on the 20 mK stage. Guided by thermal and microwave simulations, we have fabricated microwave attenuators and tested them in a 3D transmon measurement system. The performance of the attenuators was quantified by measuring the Ramsey decay time of a transmon qubit as a function of the temperature of the mixing chamber and power dissipated in the attenuator. Based on the Ramsey decay times and properties of the transmon-cavity system, we estimate the effective output noise temperature of the attenuator and compare our results to simulations.
Disturbances in equilibrium function after major earthquake
NASA Astrophysics Data System (ADS)
Honma, Motoyasu; Endo, Nobutaka; Osada, Yoshihisa; Kim, Yoshiharu; Kuriyama, Kenichi
2012-10-01
Major earthquakes were followed by a large number of aftershocks and significant outbreaks of dizziness occurred over a large area. However it is unclear why major earthquake causes dizziness. We conducted an intergroup trial on equilibrium dysfunction and psychological states associated with equilibrium dysfunction in individuals exposed to repetitive aftershocks versus those who were rarely exposed. Greater equilibrium dysfunction was observed in the aftershock-exposed group under conditions without visual compensation. Equilibrium dysfunction in the aftershock-exposed group appears to have arisen from disturbance of the inner ear, as well as individual vulnerability to state anxiety enhanced by repetitive exposure to aftershocks. We indicate potential effects of autonomic stress on equilibrium function after major earthquake. Our findings may contribute to risk management of psychological and physical health after major earthquakes with aftershocks, and allow development of a new empirical approach to disaster care after such events.
Probing local equilibrium in nonequilibrium fluids.
del Pozo, J J; Garrido, P L; Hurtado, P I
2015-08-01
We use extensive computer simulations to probe local thermodynamic equilibrium (LTE) in a quintessential model fluid, the two-dimensional hard-disks system. We show that macroscopic LTE is a property much stronger than previously anticipated, even in the presence of important finite-size effects, revealing a remarkable bulk-boundary decoupling phenomenon in fluids out of equilibrium. This allows us to measure the fluid's equation of state in simulations far from equilibrium, with an excellent accuracy comparable to the best equilibrium simulations. Subtle corrections to LTE are found in the fluctuations of the total energy which strongly point to the nonlocality of the nonequilibrium potential governing the fluid's macroscopic behavior out of equilibrium. PMID:26382354
Equilibrium and Stability Calculations in HIT-SI
NASA Astrophysics Data System (ADS)
Hansen, Chris; Marklin, George; Jarboe, Thomas
2012-10-01
The PSI-TET equilibrium code solves for solutions to the Ideal MHD equilibrium equation μ0j = λB in arbitrary 3D geometry. A mimetic discretization on a tetrahedral mesh is employed, with up to 3rd order spatial representation. Geometric and polynomial multigrid along with a hybrid MPI/OpenMP parallelism model is used to provide solver scalability. Lambda is allowed to vary across flux surfaces but must be constant in stochastic regions. A scalar flux surface variable is computed by solving an artificial diffusion problem with a large ratio of parallel to perpendicular thermal conductivity. A fixed lambda profile, specified as a function of this flux surface variable, is defined. Equilibria in HIT-SI have been computed for the homogenous (spheromak) and inhomogeneous (injector) fields separately. Combined equilibria of interest with injector driving have also been computed for various lambda profiles. A linearized Ideal MHD module has been developed to evaluate the stability properties of computed equilbria. Equilibrium states and stability analysis will be presented for a range of lambda profiles. Results will also be presented comparing linear to high order Mimetic representations and Mimetic to standard nodal finite element representations. Work supported by DOE.
Comparing Science Achievement Constructs: Targeted and Achieved
ERIC Educational Resources Information Center
Ferrara, Steve; Duncan, Teresa
2011-01-01
This article illustrates how test specifications based solely on academic content standards, without attention to other cognitive skills and item response demands, can fall short of their targeted constructs. First, the authors inductively describe the science achievement construct represented by a statewide sixth-grade science proficiency test.…
Varieties of Achievement Motivation.
ERIC Educational Resources Information Center
Kukla, Andre; Scher, Hal
1986-01-01
A recent article by Nicholls on achievement motivation is criticized on three points: (1) definitions of achievement motives are ambiguous; (2) behavioral consequences predicted do not follow from explicit theoretical assumptions; and (3) Nicholls's account of the relation between his theory and other achievement theories is factually incorrect.…
Motivation and School Achievement.
ERIC Educational Resources Information Center
Maehr, Martin L.; Archer, Jennifer
Addressing the question, "What can be done to promote school achievement?", this paper summarizes the literature on motivation relating to classroom achievement and school effectiveness. Particular attention is given to how values, ideology, and various cultural patterns impinge on classroom performance and serve to enhance motivation to achieve.…
Mobility and Reading Achievement.
ERIC Educational Resources Information Center
Waters, Theresa Z.
A study examined the effect of geographic mobility on elementary school students' achievement. Although such mobility, which requires students to make multiple moves among schools, can have a negative impact on academic achievement, the hypothesis for the study was that it was not a determining factor in reading achievement test scores. Subjects…
ERIC Educational Resources Information Center
Kirby, John R.
Two studies examined the effectiveness of the PASS (Planning, Attention, Simultaneous, and Successive cognitive processes) theory of intelligence in predicting reading achievement scores of normally achieving children and distinguishing children with reading disabilities from normally achieving children. The first study dealt with predicting…
Equilibrium of non-neutral plasmas with weak axisymmetric magnetic perturbations
Rome, M.; Kotelnikov, I.; Kabantsev, A.
2006-10-18
The effect of weak external axisymmetric magnetic and electrostatic perturbations on the equilibrium of a non-neutral plasma confined in a Malmberg-Penning trap is analyzed. A semi-analytic solution for the potential variations inside the trap is found in a paraxial limit of the perturbations for the case of global thermal equilibrium. The populations of magnetically and electrostatically trapped particles created by the external perturbations are characterized, and their fractions are calculated explicitly for a bi-Maxwellian distribution function. 2D numerical simulations of the thermal equilibrium of a pure electron plasma in the presence of axial magnetic field perturbations are performed to check the limits of validity of the analytical 1D approximation.
Out-of-equilibrium phenomena and Transport in Cold Atoms
NASA Astrophysics Data System (ADS)
Giamarchi, Thierry
superfluidity and thermally activated transport which leads to a conductance minimum and poses several theoretical questions for its theoretical description. Work supported in part by Swiss NSF under division II and the ARO-MURI Non-equilibrium Many-body Dynamics Grant (W911NF-14-1-0003).
Warm-fluid description of intense beam equilibrium and electrostatic stability properties
Lund, S.M.; Davidson, R.C.
1998-08-01
A nonrelativistic warm-fluid model is employed in the electrostatic approximation to investigate the equilibrium and stability properties of an unbunched, continuously focused intense ion beam. A closed macroscopic model is obtained by truncating the hierarchy of moment equations by the assumption of negligible heat flow. Equations describing self-consistent fluid equilibria are derived and elucidated with examples corresponding to thermal equilibrium, the Kapchinskij{endash}Vladimirskij (KV) equilibrium, and the waterbag equilibrium. Linearized fluid equations are derived that describe the evolution of small-amplitude perturbations about an arbitrary equilibrium. Electrostatic stability properties are analyzed in detail for a cold beam with step-function density profile, and then for axisymmetric flute perturbations with {partial_derivative}/{partial_derivative}{theta}=0 and {partial_derivative}/{partial_derivative}z=0 about a warm-fluid KV beam equilibrium. The radial eigenfunction describing axisymmetric flute perturbations about the KV equilibrium is found to be {ital identical} to the eigenfunction derived in a full kinetic treatment. However, in contrast to the kinetic treatment, the warm-fluid model predicts stable oscillations. None of the instabilities that are present in a kinetic description are obtained in the fluid model. A careful comparison of the mode oscillation frequencies associated with the fluid and kinetic models is made in order to delineate which stability features of a KV beam are model-dependent and which may have general applicability. {copyright} {ital 1998 American Institute of Physics.}
Turbulence Modeling Effects on the Prediction of Equilibrium States of Buoyant Shear Flows
NASA Technical Reports Server (NTRS)
Zhao, C. Y.; So, R. M. C.; Gatski, T. B.
2001-01-01
The effects of turbulence modeling on the prediction of equilibrium states of turbulent buoyant shear flows were investigated. The velocity field models used include a two-equation closure, a Reynolds-stress closure assuming two different pressure-strain models and three different dissipation rate tensor models. As for the thermal field closure models, two different pressure-scrambling models and nine different temperature variance dissipation rate, Epsilon(0) equations were considered. The emphasis of this paper is focused on the effects of the Epsilon(0)-equation, of the dissipation rate models, of the pressure-strain models and of the pressure-scrambling models on the prediction of the approach to equilibrium turbulence. Equilibrium turbulence is defined by the time rate (if change of the scaled Reynolds stress anisotropic tensor and heat flux vector becoming zero. These conditions lead to the equilibrium state parameters. Calculations show that the Epsilon(0)-equation has a significant effect on the prediction of the approach to equilibrium turbulence. For a particular Epsilon(0)-equation, all velocity closure models considered give an equilibrium state if anisotropic dissipation is accounted for in one form or another in the dissipation rate tensor or in the Epsilon(0)-equation. It is further found that the models considered for the pressure-strain tensor and the pressure-scrambling vector have little or no effect on the prediction of the approach to equilibrium turbulence.
Off-equilibrium photon production during the chiral phase transition
Michler, Frank; Hees, Hendrik van; Dietrich, Dennis D.; Leupold, Stefan; Greiner, Carsten
2013-09-15
In the early stage of ultrarelativistic heavy-ion collisions chiral symmetry is restored temporarily. During this so-called chiral phase transition, the quark masses change from their constituent to their bare values. This mass shift leads to the spontaneous non-perturbative creation of quark–antiquark pairs, which effectively contributes to the formation of the quark–gluon plasma. We investigate the photon production induced by this creation process. We provide an approach that eliminates possible unphysical contributions from the vacuum polarization and renders the resulting photon spectra integrable in the ultraviolet domain. The off-equilibrium photon numbers are of quadratic order in the perturbative coupling constants while a thermal production is only of quartic order. Quantitatively, we find, however, that for the most physical mass-shift scenarios and for photon momenta larger than 1 GeV the off-equilibrium processes contribute less photons than the thermal processes. -- Highlights: •We investigate first-order photon emission arising from the chiral mass shift. •We provide an ansatz eliminating possible unphysical vacuum contributions. •Our ansatz leads to photon spectra being integrable in the ultraviolet domain.
Local Nash Equilibrium in Social Networks
Zhang, Yichao; Aziz-Alaoui, M. A.; Bertelle, Cyrille; Guan, Jihong
2014-01-01
Nash equilibrium is widely present in various social disputes. As of now, in structured static populations, such as social networks, regular, and random graphs, the discussions on Nash equilibrium are quite limited. In a relatively stable static gaming network, a rational individual has to comprehensively consider all his/her opponents' strategies before they adopt a unified strategy. In this scenario, a new strategy equilibrium emerges in the system. We define this equilibrium as a local Nash equilibrium. In this paper, we present an explicit definition of the local Nash equilibrium for the two-strategy games in structured populations. Based on the definition, we investigate the condition that a system reaches the evolutionary stable state when the individuals play the Prisoner's dilemma and snow-drift game. The local Nash equilibrium provides a way to judge whether a gaming structured population reaches the evolutionary stable state on one hand. On the other hand, it can be used to predict whether cooperators can survive in a system long before the system reaches its evolutionary stable state for the Prisoner's dilemma game. Our work therefore provides a theoretical framework for understanding the evolutionary stable state in the gaming populations with static structures. PMID:25169150
Jolley, Kenny; Gill, Simon P.A.
2009-10-20
A method for controlling the thermal boundary conditions of non-equilibrium molecular dynamics simulations is presented. The method is simple to implement into a conventional molecular dynamics code and independent of the atomistic model employed. It works by regulating the temperature in a thermostatted boundary region by feedback control to achieve the desired temperature at the edge of an inner region where the true atomistic dynamics are retained. This is necessary to avoid intrinsic boundary effects in non-equilibrium molecular dynamics simulations. Three thermostats are investigated: the global deterministic Nose-Hoover thermostat and two local stochastic thermostats, Langevin and stadium damping. The latter thermostat is introduced to avoid the adverse reflection of phonons that occurs at an abrupt interface. The method is then extended to allow atomistic/continuum models to be thermally coupled concurrently for the analysis of large steady state and transient heat conduction problems. The effectiveness of the algorithm is demonstrated for the example of heat flow down a three-dimensional atomistic rod of uniform cross-section subjected to a variety of boundary conditions.
NASA Astrophysics Data System (ADS)
Babaei, Hasan; Keblinski, Pawel; Khodadadi, J. M.
2013-02-01
It has been recently demonstrated through experiments that the observed high enhancements in thermal conductivity of nanofluids are due to aggregation of nanoparticles rather than the previously stated mechanism of the Brownian motion-induced micro-convection. In this paper, we use equilibrium molecular dynamics simulations to investigate the role of micro-convection on the thermal conductivity of well-dispersed nanofluids. We show that while the individual terms in the heat current autocorrelation function associated with nanoparticle diffusion achieve significant values, these terms essentially cancel each other if correctly defined average enthalpy expressions are subtracted. Otherwise, erroneous thermal conductivity enhancements will be predicted, which are attributed to Brownian motion-induced micro-convection. Consequently, micro-convection does not contribute noticeably to the thermal conductivity and the predicted thermal conductivity enhancements are consistent with the effective medium theory.
NASA Astrophysics Data System (ADS)
Joulain, Karl; Drevillon, Jérémie; Ezzahri, Younès; Ordonez-Miranda, Jose
2016-05-01
We demonstrate that a thermal transistor can be made up with a quantum system of three interacting subsystems, coupled to a thermal reservoir each. This thermal transistor is analogous to an electronic bipolar one with the ability to control the thermal currents at the collector and at the emitter with the imposed thermal current at the base. This is achieved by determining the heat fluxes by means of the strong-coupling formalism. For the case of three interacting spins, in which one of them is coupled to the other two, that are not directly coupled, it is shown that high amplification can be obtained in a wide range of energy parameters and temperatures. The proposed quantum transistor could, in principle, be used to develop devices such as a thermal modulator and a thermal amplifier in nanosystems.
Joulain, Karl; Drevillon, Jérémie; Ezzahri, Younès; Ordonez-Miranda, Jose
2016-05-20
We demonstrate that a thermal transistor can be made up with a quantum system of three interacting subsystems, coupled to a thermal reservoir each. This thermal transistor is analogous to an electronic bipolar one with the ability to control the thermal currents at the collector and at the emitter with the imposed thermal current at the base. This is achieved by determining the heat fluxes by means of the strong-coupling formalism. For the case of three interacting spins, in which one of them is coupled to the other two, that are not directly coupled, it is shown that high amplification can be obtained in a wide range of energy parameters and temperatures. The proposed quantum transistor could, in principle, be used to develop devices such as a thermal modulator and a thermal amplifier in nanosystems. PMID:27258859
Gas absorption using a nanofluid solvent: kinetic and equilibrium study
NASA Astrophysics Data System (ADS)
Azizi, S.; Peyghambarzadeh, S. M.; Saremi, M.; Tahmasebi, H.
2014-12-01
An experimental study has been performed to explore gas absorption in a nanofluid solvent. Propane and propylene were separately absorbed in a non-aqueous based nanofluid composed of N-methyl 2-pyrolidone (NMP) + small amount of TiO2 nanoparticle. Absorption was performed at different initial pressures and nanoparticle concentrations. Results showed that the addition of small amount of nanoparticle enhances the rate of absorption. Nanofluid decreased the time needed to achieve equilibrium and increased the maximum amount of gas absorbed.
Non-equilibrium and unsteady fluid degassing during slow decompression
NASA Astrophysics Data System (ADS)
Hammer, Julia E.; Manga, Michael; Cashman, Katharine V.
Decompression experiments were performed on corn syrup-water solutions in order to investigate the effect of viscosity on processes of vesiculation and degassing at low to moderate degrees of volatile supersaturation. Repeat experiments demonstrated similar long term vesiculation behavior at moderate decompression rates despite highly variable initial nucleation styles. Results suggest that magmas may not necessarily achieve chemical equilibrium by vapor exsolution and may require viscosity-dependent critical supersaturations in order to vesiculate. Vesiculation also increased the ambient pressure and decreased supersaturations, resulting in unsteady degassing.
A novel bistable thermally actuated snap-through actuator for out-of-plane deflection
NASA Astrophysics Data System (ADS)
Yu, Kevin; Michael, Aron; Kwok, Chee Y.
2004-04-01
In this paper , the importance of boundary conditions for two- way bistable thermal snapping action is analysed by Ansys simulations. Several designs are developed and modified into a novel bistable actuator for out of plane deflection. It consists of 4 long epi-silicon single layered legs , a 1200um x 40um x 3um microbeam and 4 spring-supports in which both are polysilicon/oxide/episilicon layered. Buckling of the released structure is achieved by the compressive residual stress remaining in the oxide layer as a result of the processing. The structure switches between two stable equilibrium states by heating the legs and then heating one of the polysilicon layers to produce the thermal moment needed for snapping to occur, hence achieving two-way bistable operation.
Finite beta plasma equilibrium in toroidally linked mirrors
Ilgisonis, V.I.; Berk, H.L.; Pastukhov, V.P.
1993-07-01
The problem of finite pressure plasma equilibrium in a system with closed magnetic field lines consisting of quadrupole mirrors linked by simple toroidal cells with elliptical cross-sections is analyzed. An appropriate analytical procedure is developed, that uses conformal mapping techniques, which enables one to obtain the magnetic field structure for the free boundary equilibrium problem. This method has general applicability for finding analytic solutions of the two-dimensional Dirichlet problem outside of an arbitrary closed contour. Using this method, the deformations of the plasma equilibrium configuration due to finite plasma pressure in the toroidal cell are calculated analytically to the second order in {lambda}-expansion, where {lambda} {approximately} {beta}/{epsilon}E, {beta} is the ratio of plasma pressure to the magnetic field pressure, {epsilon} is the inverse aspect ratio and E is the ellipticity of the plasma cross-section. The outer displacement of the plasma column is shown to depend nonlinearly on the increase of plasma pressure, and does not prevent the achievement of substantial {beta} {approximately} 10% in the toroidal cells.
The Conceptual Change Approach to Teaching Chemical Equilibrium
ERIC Educational Resources Information Center
Canpolat, Nurtac; Pinarbasi, Tacettin; Bayrakceken, Samih; Geban, Omer
2006-01-01
This study investigates the effect of a conceptual change approach over traditional instruction on students' understanding of chemical equilibrium concepts (e.g. dynamic nature of equilibrium, definition of equilibrium constant, heterogeneous equilibrium, qualitative interpreting of equilibrium constant, changing the reaction conditions). This…
Dynamic thermal environment and thermal comfort.
Zhu, Y; Ouyang, Q; Cao, B; Zhou, X; Yu, J
2016-02-01
Research has shown that a stable thermal environment with tight temperature control cannot bring occupants more thermal comfort. Instead, such an environment will incur higher energy costs and produce greater CO2 emissions. Furthermore, this may lead to the degeneration of occupants' inherent ability to combat thermal stress, thereby weakening thermal adaptability. Measured data from many field investigations have shown that the human body has a higher acceptance to the thermal environment in free-running buildings than to that in air-conditioned buildings with similar average parameters. In naturally ventilated environments, occupants have reported superior thermal comfort votes and much greater thermal comfort temperature ranges compared to air-conditioned environments. This phenomenon is an integral part of the adaptive thermal comfort model. In addition, climate chamber experiments have proven that people prefer natural wind to mechanical wind in warm conditions; in other words, dynamic airflow can provide a superior cooling effect. However, these findings also indicate that significant questions related to thermal comfort remain unanswered. For example, what is the cause of these phenomena? How we can build a comfortable and healthy indoor environment for human beings? This article summarizes a series of research achievements in recent decades, tries to address some of these unanswered questions, and attempts to summarize certain problems for future research. PMID:26171688
An Elementary Discussion of Chemical Equilibrium.
ERIC Educational Resources Information Center
David, Carl W.
1988-01-01
This discussion uses a more difficult reaction as the prototype to derive the standard equation for chemical equilibrium. It can be used by students who can understand and use partial derivatives. (CW)
Spreadsheet Templates for Chemical Equilibrium Calculations.
ERIC Educational Resources Information Center
Joshi, Bhairav D.
1993-01-01
Describes two general spreadsheet templates to carry out all types of one-equation chemical equilibrium calculations encountered by students in undergraduate chemistry courses. Algorithms, templates, macros, and representative examples are presented to illustrate the approach. (PR)
Stochastic approach to equilibrium and nonequilibrium thermodynamics
NASA Astrophysics Data System (ADS)
Tomé, Tânia; de Oliveira, Mário J.
2015-04-01
We develop the stochastic approach to thermodynamics based on stochastic dynamics, which can be discrete (master equation) and continuous (Fokker-Planck equation), and on two assumptions concerning entropy. The first is the definition of entropy itself and the second the definition of entropy production rate, which is non-negative and vanishes in thermodynamic equilibrium. Based on these assumptions, we study interacting systems with many degrees of freedom in equilibrium or out of thermodynamic equilibrium and how the macroscopic laws are derived from the stochastic dynamics. These studies include the quasiequilibrium processes; the convexity of the equilibrium surface; the monotonic time behavior of thermodynamic potentials, including entropy; the bilinear form of the entropy production rate; the Onsager coefficients and reciprocal relations; and the nonequilibrium steady states of chemical reactions.
Equilibrium Reconstruction on the Large Helical Device
Samuel A. Lazerson, D. Gates, D. Monticello, H. Neilson, N. Pomphrey, A. Reiman S. Sakakibara, and Y. Suzuki
2012-07-27
Equilibrium reconstruction is commonly applied to axisymmetric toroidal devices. Recent advances in computational power and equilibrium codes have allowed for reconstructions of three-dimensional fields in stellarators and heliotrons. We present the first reconstructions of finite beta discharges in the Large Helical Device (LHD). The plasma boundary and magnetic axis are constrained by the pressure profile from Thomson scattering. This results in a calculation of plasma beta without a-priori assumptions of the equipartition of energy between species. Saddle loop arrays place additional constraints on the equilibrium. These reconstruction utilize STELLOPT, which calls VMEC. The VMEC equilibrium code assumes good nested flux surfaces. Reconstructed magnetic fields are fed into the PIES code which relaxes this constraint allowing for the examination of the effect of islands and stochastic regions on the magnetic measurements.
Points of Equilibrium in Electrostatic Fields.
ERIC Educational Resources Information Center
Rogers, Peter J.
1979-01-01
Discusses the electric field line pattern for four equal charges of the same sign placed at the corners of a square. The electric field intensity and the point of equilibrium are interpreted, taking into account three dimensions. (HM)
IEHI: Ionization Equilibrium for Heavy Ions
NASA Astrophysics Data System (ADS)
Cranmer, Steven R.
2015-07-01
IEHI, written in Fortran, outputs a simple "coronal" ionization equilibrium (i.e., collisional ionization and auto-ionization balanced by radiative and dielectronic recombination) for a plasma at a given electron temperature.
Surface roughness effects on equilibrium temperature.
NASA Technical Reports Server (NTRS)
Houchens, A. F.; Hering, R. G.
1972-01-01
An analysis is presented for evaluation of equilibrium temperature distribution on radiatively adiabatic, adjoint planes which are uniformly irradiated by a collimated solar flux. The analysis employs a semigrey spectral model. Radiation properties for surface emitted radiation are obtained from the expressions of electromagnetic theory for smooth surfaces. Rough surface properties for solar radiation are given by the Beckmann bidirectional reflectance model. Numerical solutions to the governing equations yield equilibrium temperature distributions for a range of the influencing parameters. Surface roughness has little influence on equilibrium temperature for materials with high values for solar absorptance. However, for low or intermediate values of solar absorptance, roughness effects on the spatial distribution of reflected solar radiation can significantly alter equilibrium temperature particularly at surface elements where radiant interaction is small.
Stochastic approach to equilibrium and nonequilibrium thermodynamics.
Tomé, Tânia; de Oliveira, Mário J
2015-04-01
We develop the stochastic approach to thermodynamics based on stochastic dynamics, which can be discrete (master equation) and continuous (Fokker-Planck equation), and on two assumptions concerning entropy. The first is the definition of entropy itself and the second the definition of entropy production rate, which is non-negative and vanishes in thermodynamic equilibrium. Based on these assumptions, we study interacting systems with many degrees of freedom in equilibrium or out of thermodynamic equilibrium and how the macroscopic laws are derived from the stochastic dynamics. These studies include the quasiequilibrium processes; the convexity of the equilibrium surface; the monotonic time behavior of thermodynamic potentials, including entropy; the bilinear form of the entropy production rate; the Onsager coefficients and reciprocal relations; and the nonequilibrium steady states of chemical reactions. PMID:25974471
SRB thermal curtain design support
NASA Technical Reports Server (NTRS)
Dixon, Carl A.; Lundblad, Wayne E.; Koenig, John R.
1992-01-01
Improvements in SRB Thermal Curtain were identified by thermal design featuring: selection of materials capable of thermal protection and service temperatures by tri-layering quartz, S2 glass, and Kevlar in thinner cross section; weaving in single piece (instead of 24 sections) to achieve improved strength; and weaving to reduce manufacturing cost with angle interlock construction.
The Theory of Variances in Equilibrium Reconstruction
Zakharov, Leonid E.; Lewandowski, Jerome; Foley, Elizabeth L.; Levinton, Fred M.; Yuh, Howard Y.; Drozdov, Vladimir; McDonald, Darren
2008-01-14
The theory of variances of equilibrium reconstruction is presented. It complements existing practices with information regarding what kind of plasma profiles can be reconstructed, how accurately, and what remains beyond the abilities of diagnostic systems. The σ-curves, introduced by the present theory, give a quantitative assessment of quality of effectiveness of diagnostic systems in constraining equilibrium reconstructions. The theory also suggests a method for aligning the accuracy of measurements of different physical nature.
Edge Equilibrium Code (EEC) For Tokamaks
Li, Xujling
2014-02-24
The edge equilibrium code (EEC) described in this paper is developed for simulations of the near edge plasma using the finite element method. It solves the Grad-Shafranov equation in toroidal coordinate and uses adaptive grids aligned with magnetic field lines. Hermite finite elements are chosen for the numerical scheme. A fast Newton scheme which is the same as implemented in the equilibrium and stability code (ESC) is applied here to adjust the grids
Accurate equilibrium structures of fluoro- and chloroderivatives of methane
NASA Astrophysics Data System (ADS)
Vogt, Natalja; Demaison, Jean; Rudolph, Heinz Dieter
2014-11-01
This work is a systematic study of molecular structure of fluoro-, chloro-, and fluorochloromethanes. For the first time, the accurate ab initio structure is computed for 10 molecules (CF4, CClF3, CCl2F2, CCl3F, CHClF2, CHCl2F, CH2F2, CH2ClF, CH2Cl2, and CCl4) at the coupled cluster level of electronic structure theory including single and double excitations augmented by a perturbational estimate of the effects of connected triple excitations [CCSD(T)] with all electrons being correlated and Gaussian basis sets of at least quadruple-ζ quality. Furthermore, when possible, namely for the molecules CH2F2, CH2Cl2, CH2ClF, CHClF2, and CCl2F2, accurate semi-experimental equilibrium (rSEe) structure has also been determined. This is achieved through a least-squares structural refinement procedure based on the equilibrium rotational constants of all available isotopomers, determined by correcting the experimental ground-state rotational constants with computed ab initio vibration-rotation interaction constants and electronic g-factors. The computed and semi-experimental equilibrium structures are in excellent agreement with each other, but the rSEe structure is generally more accurate, in particular for the CF and CCl bond lengths. The carbon-halogen bond length is discussed within the framework of the ligand close-packing model as a function of the atomic charges. For this purpose, the accurate equilibrium structures of some other molecules with alternative ligands, such as CH3Li, CF3CCH, and CF3CN, are also computed.
Effect of cooling rate on achieving thermodynamic equilibrium in uranium-plutonium mixed oxides
NASA Astrophysics Data System (ADS)
Vauchy, Romain; Belin, Renaud C.; Robisson, Anne-Charlotte; Hodaj, Fiqiri
2016-02-01
In situ X-ray diffraction was used to study the structural changes occurring in uranium-plutonium mixed oxides U1-yPuyO2-x with y = 0.15; 0.28 and 0.45 during cooling from 1773 K to room-temperature under He + 5% H2 atmosphere. We compare the fastest and slowest cooling rates allowed by our apparatus i.e. 2 K s-1 and 0.005 K s-1, respectively. The promptly cooled samples evidenced a phase separation whereas samples cooled slowly did not due to their complete oxidation in contact with the atmosphere during cooling. Besides the composition of the annealing gas mixture, the cooling rate plays a major role on the control of the Oxygen/Metal ratio (O/M) and then on the crystallographic properties of the U1-yPuyO2-x uranium-plutonium mixed oxides.
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.
Heritability of Creative Achievement
ERIC Educational Resources Information Center
Piffer, Davide; Hur, Yoon-Mi
2014-01-01
Although creative achievement is a subject of much attention to lay people, the origin of individual differences in creative accomplishments remain poorly understood. This study examined genetic and environmental influences on creative achievement in an adult sample of 338 twins (mean age = 26.3 years; SD = 6.6 years). Twins completed the Creative…
Confronting the Achievement Gap
ERIC Educational Resources Information Center
Gardner, David
2007-01-01
This article talks about the large achievement gap between children of color and their white peers. The reasons for the achievement gap are varied. First, many urban minorities come from a background of poverty. One of the detrimental effects of growing up in poverty is receiving inadequate nourishment at a time when bodies and brains are rapidly…
States Address Achievement Gaps.
ERIC Educational Resources Information Center
Christie, Kathy
2002-01-01
Summarizes 2 state initiatives to address the achievement gap: North Carolina's report by the Advisory Commission on Raising Achievement and Closing Gaps, containing an 11-point strategy, and Kentucky's legislation putting in place 10 specific processes. The North Carolina report is available at www.dpi.state.nc.us.closingthegap; Kentucky's…
Wechsler Individual Achievement Test.
ERIC Educational Resources Information Center
Taylor, Ronald L.
1999-01-01
This article describes the Wechsler Individual Achievement Test, a comprehensive measure of achievement for individuals in grades K-12. Eight subtests assess mathematics reasoning, spelling, reading comprehension, numerical operations, listening comprehension, oral expression, and written expression. Its administration, standardization,…
Inverting the Achievement Pyramid
ERIC Educational Resources Information Center
White-Hood, Marian; Shindel, Melissa
2006-01-01
Attempting to invert the pyramid to improve student achievement and increase all students' chances for success is not a new endeavor. For decades, educators have strategized, formed think tanks, and developed school improvement teams to find better ways to improve the achievement of all students. Currently, the No Child Left Behind Act (NCLB) is…
ERIC Educational Resources Information Center
Ohio State Dept. of Education, Columbus. Trade and Industrial Education Service.
The Ohio Trade and Industrial Education Achievement Test battery is comprised of seven basic achievement tests: Machine Trades, Automotive Mechanics, Basic Electricity, Basic Electronics, Mechanical Drafting, Printing, and Sheet Metal. The tests were developed by subject matter committees and specialists in testing and research. The Ohio Trade and…
General Achievement Trends: Maryland
ERIC Educational Resources Information Center
Center on Education Policy, 2009
2009-01-01
This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…
General Achievement Trends: Arkansas
ERIC Educational Resources Information Center
Center on Education Policy, 2009
2009-01-01
This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…
General Achievement Trends: Idaho
ERIC Educational Resources Information Center
Center on Education Policy, 2009
2009-01-01
This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…
General Achievement Trends: Nebraska
ERIC Educational Resources Information Center
Center on Education Policy, 2009
2009-01-01
This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…
General Achievement Trends: Colorado
ERIC Educational Resources Information Center
Center on Education Policy, 2009
2009-01-01
This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…
General Achievement Trends: Iowa
ERIC Educational Resources Information Center
Center on Education Policy, 2009
2009-01-01
This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…
General Achievement Trends: Hawaii
ERIC Educational Resources Information Center
Center on Education Policy, 2009
2009-01-01
This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…
General Achievement Trends: Kentucky
ERIC Educational Resources Information Center
Center on Education Policy, 2009
2009-01-01
This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…
General Achievement Trends: Florida
ERIC Educational Resources Information Center
Center on Education Policy, 2009
2009-01-01
This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…
General Achievement Trends: Texas
ERIC Educational Resources Information Center
Center on Education Policy, 2009
2009-01-01
This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…
General Achievement Trends: Oregon
ERIC Educational Resources Information Center
Center on Education Policy, 2009
2009-01-01
This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…
General Achievement Trends: Virginia
ERIC Educational Resources Information Center
Center on Education Policy, 2009
2009-01-01
This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…
ERIC Educational Resources Information Center
Education Digest: Essential Readings Condensed for Quick Review, 2004
2004-01-01
Is the concept of "honor roll" obsolete? The honor roll has always been a way for schools to recognize the academic achievement of their students. But does it motivate students? In this article, several elementary school principals share their views about honoring student achievement. Among others, Virginia principal Nancy Moga said that students…
ERIC Educational Resources Information Center
Martinez, Paul
The Raising Quality and Achievement Program is a 3-year initiative to support further education (FE) colleges in the United Kingdom in their drive to improve students' achievement and the quality of provision. The program offers the following: (1) quality information and advice; (2) onsite support for individual colleges; (3) help with…
Achieving Perspective Transformation.
ERIC Educational Resources Information Center
Nowak, Jens
Perspective transformation is a consciously achieved state in which the individual's perspective on life is transformed. The new perspective serves as a vantage point for life's actions and interactions, affecting the way life is lived. Three conditions are basic to achieving perspective transformation: (1) "feeling" experience, i.e., getting in…
ERIC Educational Resources Information Center
Abowitz, Kathleen Knight
2011-01-01
Public schools are functionally provided through structural arrangements such as government funding, but public schools are achieved in substance, in part, through local governance. In this essay, Kathleen Knight Abowitz explains the bifocal nature of achieving public schools; that is, that schools are both subject to the unitary Public compact of…
General Achievement Trends: Tennessee
ERIC Educational Resources Information Center
Center on Education Policy, 2009
2009-01-01
This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…
ERIC Educational Resources Information Center
Fletcher, Mike; And Others
1992-01-01
This collection of seven articles examines achievement-based resourcing (ABR), the concept that the funding of educational institutions should be linked to their success in promoting student achievement, with a focus on the application of ABR to postsecondary education in the United Kingdom. The articles include: (1) "Introduction" (Mick…
Local thermodynamic equilibrium in rapidly heated high energy density plasmas
Aslanyan, V.; Tallents, G. J.
2014-06-15
Emission spectra and the dynamics of high energy density plasmas created by optical and Free Electron Lasers (FELs) depend on the populations of atomic levels. Calculations of plasma emission and ionization may be simplified by assuming Local Thermodynamic Equilibrium (LTE), where populations are given by the Saha-Boltzmann equation. LTE can be achieved at high densities when collisional processes are much more significant than radiative processes, but may not be valid if plasma conditions change rapidly. A collisional-radiative model has been used to calculate the times taken by carbon and iron plasmas to reach LTE at varying densities and heating rates. The effect of different energy deposition methods, as well as Ionization Potential Depression are explored. This work shows regimes in rapidly changing plasmas, such as those created by optical lasers and FELs, where the use of LTE is justified, because timescales for plasma changes are significantly longer than the times needed to achieve an LTE ionization balance.
Local thermodynamic equilibrium in rapidly heated high energy density plasmas
NASA Astrophysics Data System (ADS)
Aslanyan, V.; Tallents, G. J.
2014-06-01
Emission spectra and the dynamics of high energy density plasmas created by optical and Free Electron Lasers (FELs) depend on the populations of atomic levels. Calculations of plasma emission and ionization may be simplified by assuming Local Thermodynamic Equilibrium (LTE), where populations are given by the Saha-Boltzmann equation. LTE can be achieved at high densities when collisional processes are much more significant than radiative processes, but may not be valid if plasma conditions change rapidly. A collisional-radiative model has been used to calculate the times taken by carbon and iron plasmas to reach LTE at varying densities and heating rates. The effect of different energy deposition methods, as well as Ionization Potential Depression are explored. This work shows regimes in rapidly changing plasmas, such as those created by optical lasers and FELs, where the use of LTE is justified, because timescales for plasma changes are significantly longer than the times needed to achieve an LTE ionization balance.
NASA Astrophysics Data System (ADS)
Jiang, Jian-Hua; John, Sajeev
2014-07-01
We describe photonic crystal microcavities with very strong light-matter interaction to realize room-temperature, equilibrium, exciton-polariton Bose-Einstein condensation (BEC). This goal is achieved through a careful balance between strong light trapping in a photonic band gap (PBG) and large exciton density enabled by a multiple quantum-well (QW) structure with a moderate dielectric constant. This approach enables the formation of a long-lived, dense 10-μm-1-cm- scale cloud of exciton polaritons with vacuum Rabi splitting that is roughly 7% of the bare exciton-recombination energy. We introduce a woodpile photonic crystal made of Cd0.6 Mg0.4Te with a 3D PBG of 9.2% (gap-to-central-frequency ratio) that strongly focuses a planar guided optical field on CdTe QWs in the cavity. For 3-nm QWs with 5-nm barrier width, the exciton-photon coupling can be as large as ℏΩ=55 meV (i.e., a vacuum Rabi splitting of 2ℏΩ=110 meV). The exciton-recombination energy of 1.65 eV corresponds to an optical wavelength of 750 nm. For N =106 QWs embedded in the cavity, the collective exciton-photon coupling per QW (ℏΩ/√N =5.4 meV) is much larger than the state-of-the-art value of 3.3 meV, for the CdTe Fabry-Pérot microcavity. The maximum BEC temperature is limited by the depth of the dispersion minimum for the lower polariton branch, over which the polariton has a small effective mass of approximately 10-5m0, where m0 is the electron mass in vacuum. By detuning the bare exciton-recombination energy above the planar guided optical mode, a larger dispersion depth is achieved, enabling room-temperature BEC. The BEC transition temperature ranges as high as 500 K when the polariton density per QW is increased to (11aB)-2, where aB≃3.5 nm is the exciton Bohr radius and the exciton-cavity detuning is increased to 30 meV. A high-quality PBG can suppress exciton radiative decay and enhance the polariton lifetime to beyond 150 ps at room temperature, sufficient for thermal
Holographic thermalization from nonrelativistic branes
NASA Astrophysics Data System (ADS)
Roychowdhury, Dibakar
2016-05-01
In this paper, based on the fundamental principles of gauge/gravity duality and considering a global quench, we probe the physics of thermalization for certain special classes of strongly coupled nonrelativistic quantum field theories that are dual to an asymptotically Schrödinger D p brane space time. In our analysis, we note that during the prelocal stages of the thermal equilibrium the entanglement entropy has a faster growth in time compared to its relativistic cousin. However, it shows a linear growth during the postlocal stages of thermal equilibrium where the so-called tsunami velocity associated with the linear growth of the entanglement entropy saturates to that of its value corresponding to the relativistic scenario. Finally, we explore the saturation region and it turns out that one must constraint certain parameters of the theory in a specific way in order to have discontinuous transitions at the point of saturation.
Severo, Elias Taylor Durgante; Calonego, Fred Willians; Sansígolo, Cláudio Angeli; Bond, Brian
2016-01-01
In this study the effect of thermal treatment on the equilibrium moisture content, chemical composition and biological resistance to decay fungi of juvenile and mature Hevea brasiliensis wood (rubber wood) was evaluated. Samples were taken from a 53-year-old rubber wood plantation located in Tabapuã, Sao Paulo, Brazil. The samples were thermally-modified at 180°C, 200°C and 220°C. Results indicate that the thermal modification caused: (1) a significant increase in the extractive content and proportional increase in the lignin content at 220°C; (2) a significant decrease in the equilibrium moisture content, holocelluloses, arabinose, galactose and xylose content, but no change in glucose content; and (3) a significant increase in wood decay resistance against both Pycnoporus sanguineus (L.) Murrill and Gloeophyllum trabeum (Pers.) Murrill decay fungi. The greatest decay resistance was achieved from treatment at 220°C which resulted in a change in wood decay resistance class from moderately resistant to resistant. Finally, this study also demonstrated that the influence of thermal treatment in mature wood was lower than in juvenile wood. PMID:26986200
2016-01-01
In this study the effect of thermal treatment on the equilibrium moisture content, chemical composition and biological resistance to decay fungi of juvenile and mature Hevea brasiliensis wood (rubber wood) was evaluated. Samples were taken from a 53-year-old rubber wood plantation located in Tabapuã, Sao Paulo, Brazil. The samples were thermally-modified at 180°C, 200°C and 220°C. Results indicate that the thermal modification caused: (1) a significant increase in the extractive content and proportional increase in the lignin content at 220°C; (2) a significant decrease in the equilibrium moisture content, holocelluloses, arabinose, galactose and xylose content, but no change in glucose content; and (3) a significant increase in wood decay resistance against both Pycnoporus sanguineus (L.) Murrill and Gloeophyllum trabeum (Pers.) Murrill decay fungi. The greatest decay resistance was achieved from treatment at 220°C which resulted in a change in wood decay resistance class from moderately resistant to resistant. Finally, this study also demonstrated that the influence of thermal treatment in mature wood was lower than in juvenile wood. PMID:26986200
[Achievement of therapeutic objectives].
Mantilla, Teresa
2014-07-01
Therapeutic objectives for patients with atherogenic dyslipidemia are achieved by improving patient compliance and adherence. Clinical practice guidelines address the importance of treatment compliance for achieving objectives. The combination of a fixed dose of pravastatin and fenofibrate increases the adherence by simplifying the drug regimen and reducing the number of daily doses. The good tolerance, the cost of the combination and the possibility of adjusting the administration to the patient's lifestyle helps achieve the objectives for these patients with high cardiovascular risk. PMID:25043543
NASA Astrophysics Data System (ADS)
Yamaji, Youhei; Imada, Masatoshi
2016-09-01
Relaxation of electrons in a Hubbard ring coupled to a dissipative bosonic bath is studied to simulate the pump-probe photoemission measurement. From this insight, we propose an experimental method of eliciting the unoccupied part of single-particle spectra at the equilibrium of doped Mott insulators. We reveal first that the effective temperatures of distribution functions and electronic spectra are different during the relaxation, which makes the frequently employed thermalization picture inappropriate. Contrary to the conventional analysis, we show that the unoccupied spectra at equilibrium can be detected as the states that relax faster.
Exponential trend to equilibrium for the inelastic Boltzmann equation driven by a particle bath
NASA Astrophysics Data System (ADS)
Cañizo, José A.; Lods, Bertrand
2016-05-01
We consider the spatially homogeneous Boltzmann equation for inelastic hard spheres (with constant restitution coefficient α \\in (0,1) ) under the thermalization induced by a host medium with a fixed Maxwellian distribution. We prove that the solution to the associated initial-value problem converges exponentially fast towards the unique equilibrium solution. The proof combines a careful spectral analysis of the linearised semigroup as well as entropy estimates. The trend towards equilibrium holds in the weakly inelastic regime in which α is close to 1, and the rate of convergence is explicit and depends solely on the spectral gap of the elastic linear collision operator.
NASA Astrophysics Data System (ADS)
Yamaji, Youhei; Imada, Masatoshi
2016-09-01
Relaxation of electrons in a Hubbard model coupled to a dissipative bosonic bath is studied to simulate the pump-probe photoemission measurement. From this insight, we propose an experimental method of eliciting unoccupied part of the single-particle spectra at the equilibrium of doped-Mott insulators. We reveal first that effective temperatures of distribution functions and electronic spectra are different during the relaxation, which makes the frequently employed thermalization picture inappropriate. Contrary to the conventional analysis, we show that the unoccupied spectra at equilibrium can be detected as the states that relax faster.
Tailoring thermal conductivity of silicon/germanium nanowires utilizing core-shell architecture
NASA Astrophysics Data System (ADS)
Sarikurt, S.; Ozden, A.; Kandemir, A.; Sevik, C.; Kinaci, A.; Haskins, J. B.; Cagin, T.
2016-04-01
Low-dimensional nanostructured materials show large variations in their thermal transport properties. In this work, we investigate the influence of the core-shell architecture on nanowire (1D) thermal conductivity and evaluate its validity as a strategy to achieve a better thermoelectric performance. To obtain the thermal conductivity values, equilibrium molecular dynamics simulations are conducted for core-shell nanowires of silicon and germanium. To explore the parameter space, we have calculated thermal conductivity values of the Si-core/Ge-shell and Ge-core/Si-shell nanowires having different cross-sectional sizes and core contents at several temperatures. Our results indicate that (1) increasing the cross-sectional area of pristine Si and pristine Ge nanowires increases the thermal conductivity, (2) increasing the Ge core size in the Ge-core/Si-shell structure results in a decrease in the thermal conductivity at 300 K, (3) the thermal conductivity of the Si-core/Ge-shell nanowires demonstrates a minima at a specific core size, (4) no significant variation in the thermal conductivity is observed in nanowires for temperatures larger than 300 K, and (5) the predicted thermal conductivity within the frame of applied geometrical constraints is found to be around 10 W/(mK) for the Si and Ge core-shell architecture with a smooth interface. The value is still higher than the amorphous limit (1 W/(mK)). This represents a significant reduction in thermal conductivity with respect to their bulk crystalline and pristine nanowire forms. Furthermore, we observed additional suppression of thermal conductivity through the introduction of interface roughness to Si/Ge core-shell nanowires.
IONIZATION EQUILIBRIUM TIMESCALES IN COLLISIONAL PLASMAS
Smith, Randall K.; Hughes, John P. E-mail: jph@physics.rutgers.ed
2010-07-20
Astrophysical shocks or bursts from a photoionizing source can disturb the typical collisional plasma found in galactic interstellar media or the intergalactic medium. The spectrum emitted by this plasma contains diagnostics that have been used to determine the time since the disturbing event, although this determination becomes uncertain as the elements in the plasma return to ionization equilibrium. A general solution for the equilibrium timescale for each element arises from the elegant eigenvector method of solution to the problem of a non-equilibrium plasma described by Masai and Hughes and Helfand. In general, the ionization evolution of an element Z in a constant electron temperature plasma is given by a coupled set of Z + 1 first-order differential equations. However, they can be recast as Z uncoupled first-order differential equations using an eigenvector basis for the system. The solution is then Z separate exponential functions, with the time constants given by the eigenvalues of the rate matrix. The smallest of these eigenvalues gives the scale of the slowest return to equilibrium independent of the initial conditions, while conversely the largest eigenvalue is the scale of the fastest change in the ion population. These results hold for an ionizing plasma, a recombining plasma, or even a plasma with random initial conditions, and will allow users of these diagnostics to determine directly if their best-fit result significantly limits the timescale since a disturbance or is so close to equilibrium as to include an arbitrarily long time.
Torque equilibrium attitude control for Skylab reentry
NASA Technical Reports Server (NTRS)
Glaese, J. R.; Kennel, H. F.
1980-01-01
The method of torque equilibrium attitude control used to control the reentry of Skylab to an altitude below 150 km without the use of thruster fuel once the attitude was established is discussed. The Skylab attitude and pointing control system, which included rate gyros, sun sensors, star tracker, the Apollo telescope mount digital computer, control moment gyros and cold-gas attitude thrusters, is presented. The 12 torque equilibrium attitudes found at which aerodynamic, gravity gradient and gyroscopic torques would balance are indicated, and the three of those at which the solar power supply would be adequate for attitude control are illustrated. The equilibrium seeking method employed is then examined, and the operation and performance of the torque equilibrium attitude control system during the three weeks prior to Skylab reentry are discussed. It is concluded that the torque equilibrium attitude control method developed for Skylab was successful in performing its assigned mission, and will be valuable for the design of future, low-altitude spacecraft or tethered vehicles.
Predicting Achievement and Motivation.
ERIC Educational Resources Information Center
Uguroglu, Margaret; Walberg, Herbert J.
1986-01-01
Motivation and nine other factors were measured for 970 students in grades five through eight in a study of factors predicting achievement and predicting motivation. Results are discussed. (Author/MT)
Attractiveness and School Achievement
ERIC Educational Resources Information Center
Salvia, John; And Others
1977-01-01
The purpose of this study was to ascertain the relationship between rated attractiveness and two measures of school performance. Attractive children received significantly higher report cards and, to some degree, higher achievement test scores than their unattractive peers. (Author)
Student Achievement and Motivation
ERIC Educational Resources Information Center
Flammer, Gordon H.; Mecham, Robert C.
1974-01-01
Compares the lecture and self-paced methods of instruction on the basis of student motivation and achieveme nt, comparing motivating and demotivating factors in each, and their potential for motivation and achievement. (Authors/JR)
Evidence for equilibrium gels of valence-limited particles.
Dudukovic, Nikola A; Zukoski, Charles F
2014-10-21
We explore the formation and structure of gels produced from solutions of the aromatic dipeptide derivative molecule fluorenylmethoxycarbonyl-diphenylalanine (Fmoc-FF) in dimethyl sulfoxide (DMSO). Mixing these solutions with water results in the self-assembly of Fmoc-FF molecules into space-filling fibrous networks, exhibiting mechanical properties characteristic of gels. Using confocal fluorescence microscopy, we observe the gel transition in situ and find that, upon the addition of water, the solution undergoes a rapid transition to a non-equilibrium state forming ∼ 2 μm spheres, followed by the formation of fibers 5-10 nm in diameter, nucleating at a sphere surface and expanding into the solution as the remaining spheres dissolve, extending the network. The gel aging process is associated with the network becoming increasingly uniform through apparent redissolution/reaggregation of the Fmoc-FF molecules, corresponding to the observed increase in the elastic modulus to a plateau value. We demonstrate that this increase in uniformity and elastic modulus can be expedited by controlling the temperature of the system, as well as that these gels are thermally reversible, further indicating that the system is in equilibrium in its fibrous network state. X-ray scattering information suggests that the packing of the molecules within a fiber is based on π-π stacking of β-sheets, consistent with models proposed in the literature for similar systems, implying that each particle (molecule) possesses a limited number of interaction sites. These observations provide experimental evidence that these low molecular weight gelator molecules can be considered valence-limited "patchy" particles, which associate at low enough temperature to form equilibrium gels. PMID:25155031
NASA Technical Reports Server (NTRS)
Birur, Gajanana C.; Siebes, Georg; Swanson, Theodore D.; Powers, Edward I. (Technical Monitor)
2001-01-01
Thermal control of the spacecraft is typically achieved by removing heat from the spacecraft parts that tend to overheat and adding heat to the parts that tend get too cold. The equipment on the spacecraft can get very hot if it is exposed to the sun or have internal heat generation. The pans also can get very cold if they are exposed to the cold of deep space. The spacecraft and instruments must be designed to achieve proper thermal balance. The combination of the spacecraft's external thermal environment, its internal heat generation (i.e., waste heat from the operation of electrical equipment), and radiative heat rejection will determine this thermal balance. It should also be noted that this is seldom a static situation, external environmental influences and internal heat generation are normally dynamic variables which change with time. Topics discussed include thermal control system components, spacecraft mission categories, spacecraft thermal requirements, space thermal environments, thermal control hardware, launch and flight operations, advanced technologies for future spacecraft,
The automated design of materials far from equilibrium
NASA Astrophysics Data System (ADS)
Miskin, Marc Z.
Automated design is emerging as a powerful concept in materials science. By combining computer algorithms, simulations, and experimental data, new techniques are being developed that start with high level functional requirements and identify the ideal materials that achieve them. This represents a radically different picture of how materials become functional in which technological demand drives material discovery, rather than the other way around. At the frontiers of this field, materials systems previously considered too complicated can start to be controlled and understood. Particularly promising are materials far from equilibrium. Material robustness, high strength, self-healing and memory are properties displayed by several materials systems that are intrinsically out of equilibrium. These and other properties could be revolutionary, provided they can first be controlled. This thesis conceptualizes and implements a framework for designing materials that are far from equilibrium. We show how, even in the absence of a complete physical theory, design from the top down is possible and lends itself to producing physical insight. As a prototype system, we work with granular materials: collections of athermal, macroscopic identical objects, since these materials function both as an essential component of industrial processes as well as a model system for many non-equilibrium states of matter. We show that by placing granular materials in the context of design, benefits emerge simultaneously for fundamental and applied interests. As first steps, we use our framework to design granular aggregates with extreme properties like high stiffness, and softness. We demonstrate control over nonlinear effects by producing exotic aggregates that stiffen under compression. Expanding on our framework, we conceptualize new ways of thinking about material design when automatic discovery is possible. We show how to build rules that link particle shapes to arbitrary granular packing
Magnetospheric equilibrium configurations and slow adiabatic convection
NASA Technical Reports Server (NTRS)
Voigt, Gerd-Hannes
1986-01-01
This review paper demonstrates how the magnetohydrostatic equilibrium (MHE) theory can be used to describe the large-scale magnetic field configuration of the magnetosphere and its time evolution under the influence of magnetospheric convection. The equilibrium problem is reviewed, and levels of B-field modelling are examined for vacuum models, quasi-static equilibrium models, and MHD models. Results from two-dimensional MHE theory as they apply to the Grad-Shafranov equation, linear equilibria, the asymptotic theory, magnetospheric convection and the substorm mechanism, and plasma anisotropies are addressed. Results from three-dimensional MHE theory are considered as they apply to an intermediate analytical magnetospheric model, magnetotail configurations, and magnetopause boundary conditions and the influence of the IMF.
Equilibrium versus disequilibrium of barchan dunes
NASA Astrophysics Data System (ADS)
El belrhiti, Hicham; Douady, Stéphane
2011-02-01
Barchans are crescentic dunes which occur in mainly mono-directional winds. Shape, aspect ratios and velocities of these dunes have been studied as if they were in equilibrium. However, following a study of the shape and migration of 11 barchans of different sizes for 18 months in the field on Moroccan Atlantic Sahara, we show that they only appear to be in a stationary state if studied over a long timeframe (at the scale of the year or several years), but are never in equilibrium at the scale of weeks or months. Rather, they are always 'trying' to reach a possible equilibrium state but never have enough time to accomplish this. This may be the main reason for the large variation observed in previous measurements, and justifies some caution in what can be deduced from them.
MCNP modelling of the PBMR equilibrium core
Albornoz, F.; Korochinsky, S.
2006-07-01
A complete MCNP model of the PBMR equilibrium core is presented, which accounts for the same fuel regions defined in the PBMR core management code, as well as for complete fuel and reflector temperature distributions. This comprehensive 3D model is the means to calculate and characterize the neutron and photon boundary sources of the equilibrium core, and is also used to support some specific core neutronic studies needing detailed geometry modelling. Due to the geometrical modelling approach followed, an unrealistic partial cutting of fuel kernels and pebbles is introduced in the model. The variations introduced by this partial cutting both on the packing fraction and on the uranium load of the modelled core and its corresponding effect on core reactivity and flux levels, have been investigated and quantified. A complete set of high-temperature cross-section data was applied to the calculation of the PBMR equilibrium core, and its effect on the calculated core reactivity is also reported. (authors)
Analytic prediction of airplane equilibrium spin characteristics
NASA Technical Reports Server (NTRS)
Adams, W. M., Jr.
1972-01-01
The nonlinear equations of motion are solved algebraically for conditions for which an airplane is in an equilibrium spin. Constrained minimization techniques are employed in obtaining the solution. Linear characteristics of the airplane about the equilibrium points are also presented and their significance in identifying the stability characteristics of the equilibrium points is discussed. Computer time requirements are small making the method appear potentially applicable in airplane design. Results are obtained for several configurations and are compared with other analytic-numerical methods employed in spin prediction. Correlation with experimental results is discussed for one configuration for which a rather extensive data base was available. A need is indicated for higher Reynolds number data taken under conditions which more accurately simulate a spin.
NASA Astrophysics Data System (ADS)
Artem'eva, L. A.
2014-12-01
The parametric problem of equilibrium programming is examined. The mathematical programming problem, the search for a saddle-point, the multicriteria search for a Pareto point, etc. are particular cases of this parametric problem. The primal and dual variants of the extragradient method are proposed as a tool for searching for equilibrium points. The convergence of both variants is analyzed.
ERIC Educational Resources Information Center
Atasoy, Basri; Akkus, Huseyin; Kadayifci, Hakki
2009-01-01
The purpose of this study was to compare the effects of a conceptual change approach over traditional instruction on tenth-grade students' conceptual achievement in understanding chemical equilibrium. The study was conducted in two classes of the same teacher with participation of a total of 44 tenth-grade students. In this study, a…
On the thermal durability of solar prominences, or how to evaporate a prominence
NASA Technical Reports Server (NTRS)
Malherbe, J. M.; Forbes, T. G.
1986-01-01
The thermal disappearance of solar prominences under strong perturbations due to wave heating, Ohmic heating, viscous heating or conduction was investigated. Specifically, how large a thermal perturbation is needed to destroy a stable thermal equilibrium was calculated. It was found that the prominence plasma appears to be thermally very rugged. Its cold equilibrium may most likely be destroyed by either strong magnetic heating or conduction in a range of parameters which is relevant to flares.
Transport Coefficients for the NASA Lewis Chemical Equilibrium Program
NASA Technical Reports Server (NTRS)
Svehla, Roger A.
1995-01-01
The new transport property data that will be used in the NASA Lewis Research Center's Chemical Equilibrium and Applications Program (CEA) is presented. It complements a previous publication that documented the thermodynamic and transport property data then in use. Sources of the data and a brief description of the method by which the data were obtained are given. Coefficients to calculate the viscosity, thermal conductivity, and binary interactions are given for either one, or usually, two temperature intervals, typically 300 to 1000 K and 1000 to 5000 K. The form of the transport equation is the same as used previously. The number of species was reduced from the previous database. Many species for which the data were estimated were eliminated from the database. Some ionneutral interactions were added.
Non-Equilibrium Steady States for Chains of Four Rotors
NASA Astrophysics Data System (ADS)
Cuneo, N.; Eckmann, J.-P.
2016-07-01
We study a chain of four interacting rotors (rotators) connected at both ends to stochastic heat baths at different temperatures. We show that for non-degenerate interaction potentials the system relaxes, at a stretched exponential rate, to a non-equilibrium steady state (NESS). Rotors with high energy tend to decouple from their neighbors due to fast oscillation of the forces. Because of this, the energy of the central two rotors, which interact with the heat baths only through the external rotors, can take a very long time to dissipate. By appropriately averaging the oscillatory forces, we estimate the dissipation rate and construct a Lyapunov function. Compared to the chain of length three (considered previously by C. Poquet and the current authors), the new difficulty with four rotors is the appearance of resonances when both central rotors are fast. We deal with these resonances using the rapid thermalization of the two external rotors.
Putting A Human Face on Equilibrium
NASA Astrophysics Data System (ADS)
Glickstein, Neil
2005-03-01
A short biography of chemist Fritz Haber is used to personalize the abstract concepts of equilibrium chemistry for high school students in an introductory course. In addition to giving the Haber Bosch process an historic, an economic, and a scientific background the reading and subsequent discussion allows students for whom the human perspective is of paramount importance a chance to investigate the irony of balance or equilibrium in Haber's life story. Since the inclusion of the Haber biography, performance in the laboratory and on examinations for those students who are usually only partially engaged has dramatically improved.
Isodynamic axisymmetric equilibrium near the magnetic axis
Arsenin, V. V.
2013-08-15
Plasma equilibrium near the magnetic axis of an axisymmetric toroidal magnetic confinement system is described in orthogonal flux coordinates. For the case of a constant current density in the vicinity of the axis and magnetic surfaces with nearly circular cross sections, expressions for the poloidal and toroidal magnetic field components are obtained in these coordinates by using expansion in the reciprocal of the aspect ratio. These expressions allow one to easily derive relationships between quantities in an isodynamic equilibrium, in which the absolute value of the magnetic field is constant along the magnetic surface (Palumbo’s configuration)
Equilibrium stellar systems with genetic algorithms
NASA Astrophysics Data System (ADS)
Gularte, E.; Carpintero, D. D.
In 1979, M Schwarzschild showed that it is possible to build an equilibrium triaxial stellar system. However, the linear programmation used to that goal was not able to determine the uniqueness of the solution, nor even if that solution was the optimum one. Genetic algorithms are ideal tools to find a solution to this problem. In this work, we use a genetic algorithm to reproduce an equilibrium spherical stellar system from a suitable set of predefined orbits, obtaining the best solution attainable with the provided set. FULL TEXT IN SPANISH
Algorithm For Hypersonic Flow In Chemical Equilibrium
NASA Technical Reports Server (NTRS)
Palmer, Grant
1989-01-01
Implicit, finite-difference, shock-capturing algorithm calculates inviscid, hypersonic flows in chemical equilibrium. Implicit formulation chosen because overcomes limitation on mathematical stability encountered in explicit formulations. For dynamical portion of problem, Euler equations written in conservation-law form in Cartesian coordinate system for two-dimensional or axisymmetric flow. For chemical portion of problem, equilibrium state of gas at each point in computational grid determined by minimizing local Gibbs free energy, subject to local conservation of molecules, atoms, ions, and total enthalpy. Major advantage: resulting algorithm naturally stable and captures strong shocks without help of artificial-dissipation terms to damp out spurious numerical oscillations.
Far-from-equilibrium kinetic processes
NASA Astrophysics Data System (ADS)
Rubí, J. Miguel; Pérez-Madrid, Agustin
2015-12-01
We analyze the kinetics of activated processes that take place under far-from-equilibrium conditions, when the system is subjected to external driving forces or gradients or at high values of affinities. We use mesoscopic non-equilibrium thermodynamics to show that when a force is applied, the reaction rate depends on the force. In the case of a chemical reaction at high affinity values, the reaction rate is no longer constant but depends on affinity, which implies that the law of mass action is no longer valid. This result is in good agreement with the kinetic theory of reacting gases, which uses a Chapman-Enskog expansion of the probability distribution.
Dynamically defined measures and equilibrium states
NASA Astrophysics Data System (ADS)
Werner, Ivan
2011-12-01
A technique of dynamically defined measures is developed and its relation to the theory of equilibrium states is shown. The technique uses Carathéodory's method and the outer measure introduced in a previous work by I. Werner [Math. Proc. Camb. Phil. Soc. 140(2), 333-347 (2006), 10.1017/S0305004105009072]. As an application, equilibrium states for contractive Markov systems [I. Werner, J. London Math. Soc. 71(1), 236-258 (2005), 10.1112/S0024610704006088] are obtained.
Isodynamic axisymmetric equilibrium near the magnetic axis
NASA Astrophysics Data System (ADS)
Arsenin, V. V.
2013-08-01
Plasma equilibrium near the magnetic axis of an axisymmetric toroidal magnetic confinement system is described in orthogonal flux coordinates. For the case of a constant current density in the vicinity of the axis and magnetic surfaces with nearly circular cross sections, expressions for the poloidal and toroidal magnetic field components are obtained in these coordinates by using expansion in the reciprocal of the aspect ratio. These expressions allow one to easily derive relationships between quantities in an isodynamic equilibrium, in which the absolute value of the magnetic field is constant along the magnetic surface (Palumbo's configuration).
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.
Yang, Zhixin; Wang, Shaowei; Zhao, Moli; Li, Shucai; Zhang, Qiangyong
2013-01-01
The onset of double diffusive convection in a viscoelastic fluid-saturated porous layer is studied when the fluid and solid phase are not in local thermal equilibrium. The modified Darcy model is used for the momentum equation and a two-field model is used for energy equation each representing the fluid and solid phases separately. The effect of thermal non-equilibrium on the onset of double diffusive convection is discussed. The critical Rayleigh number and the corresponding wave number for the exchange of stability and over-stability are obtained, and the onset criterion for stationary and oscillatory convection is derived analytically and discussed numerically. PMID:24312193
Exploration of the Equilibrium Operating Space For NSTX-Upgrade
S.P. Gerhardt, R. Andre and J.E. Menard
2012-04-25
This paper explores a range of high-performance equilibrium scenarios available in the NSTX-Upgrade device [J.E. Menard, submitted for publication to Nuclear Fusion]. NSTX-Upgrade is a substantial upgrade to the existing NSTX device [M. Ono, et al., Nuclear Fusion 40, 557 (2000)], with significantly higher toroidal field and solenoid capabilities, and three additional neutral beam sources with significantly larger current drive efficiency. Equilibria are computed with freeboundary TRANSP, allowing a self consistent calculation of the non-inductive current drive sources, the plasma equilibrium, and poloidal field coil current, using the realistic device geometry. The thermal profiles are taken from a variety of existing NSTX discharges, and different assumptions for the thermal confinement scalings are utilized. The no-wall and idealwall n=1 stability limits are computed with the DCON code. The central and minimum safety factors are quite sensitive to many parameters: they generally increases with large outer plasmawall gaps and higher density, but can have either trend with the confinement enhancement factor. In scenarios with strong central beam current drive, the inclusion of non-classical fast ion diffusion raises qmin, decreases the pressure peaking, and generally improves the global stability, at the expense of a reduction in the non-inductive current drive fraction; cases with less beam current drive are largely insensitive to additional fast ion diffusion. The non-inductive current level is quite sensitive to the underlying confinement and profile assumptions. For instance, for BT=1.0 T and Pinj=12.6 MW, the non-inductive current level varies from 875 kA with ITER-98y,2 thermal confinement scaling and narrow thermal profiles to 1325 kA for an ST specific scaling expression and broad profiles. This sensitivity should facilitate the determination of the correct scaling of transport with current and field to use for future fully non-inductive ST devices
Heating and Cooling: Measurement of Temperature for Thermally Connected Systems.
ERIC Educational Resources Information Center
Baines, John
1995-01-01
Discusses a series of experiments to establish a significance of temperature difference in rates of cooling, to illustrate the connection between energy transfer and the consequent temperature changes for thermally connected systems that are not in equilibrium. (MKR)
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.
Sugiura, Haruka; Ito, Manami; Okuaki, Tomoya; Mori, Yoshihito; Kitahata, Hiroyuki; Takinoue, Masahiro
2016-01-01
The design, construction and control of artificial self-organized systems modelled on dynamical behaviours of living systems are important issues in biologically inspired engineering. Such systems are usually based on complex reaction dynamics far from equilibrium; therefore, the control of non-equilibrium conditions is required. Here we report a droplet open-reactor system, based on droplet fusion and fission, that achieves dynamical control over chemical fluxes into/out of the reactor for chemical reactions far from equilibrium. We mathematically reveal that the control mechanism is formulated as pulse-density modulation control of the fusion-fission timing. We produce the droplet open-reactor system using microfluidic technologies and then perform external control and autonomous feedback control over autocatalytic chemical oscillation reactions far from equilibrium. We believe that this system will be valuable for the dynamical control over self-organized phenomena far from equilibrium in chemical and biomedical studies. PMID:26786848
NASA Astrophysics Data System (ADS)
Sugiura, Haruka; Ito, Manami; Okuaki, Tomoya; Mori, Yoshihito; Kitahata, Hiroyuki; Takinoue, Masahiro
2016-01-01
The design, construction and control of artificial self-organized systems modelled on dynamical behaviours of living systems are important issues in biologically inspired engineering. Such systems are usually based on complex reaction dynamics far from equilibrium; therefore, the control of non-equilibrium conditions is required. Here we report a droplet open-reactor system, based on droplet fusion and fission, that achieves dynamical control over chemical fluxes into/out of the reactor for chemical reactions far from equilibrium. We mathematically reveal that the control mechanism is formulated as pulse-density modulation control of the fusion-fission timing. We produce the droplet open-reactor system using microfluidic technologies and then perform external control and autonomous feedback control over autocatalytic chemical oscillation reactions far from equilibrium. We believe that this system will be valuable for the dynamical control over self-organized phenomena far from equilibrium in chemical and biomedical studies.
Sugiura, Haruka; Ito, Manami; Okuaki, Tomoya; Mori, Yoshihito; Kitahata, Hiroyuki; Takinoue, Masahiro
2016-01-01
The design, construction and control of artificial self-organized systems modelled on dynamical behaviours of living systems are important issues in biologically inspired engineering. Such systems are usually based on complex reaction dynamics far from equilibrium; therefore, the control of non-equilibrium conditions is required. Here we report a droplet open-reactor system, based on droplet fusion and fission, that achieves dynamical control over chemical fluxes into/out of the reactor for chemical reactions far from equilibrium. We mathematically reveal that the control mechanism is formulated as pulse-density modulation control of the fusion–fission timing. We produce the droplet open-reactor system using microfluidic technologies and then perform external control and autonomous feedback control over autocatalytic chemical oscillation reactions far from equilibrium. We believe that this system will be valuable for the dynamical control over self-organized phenomena far from equilibrium in chemical and biomedical studies. PMID:26786848
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
Punctuated equilibrium in an evolving bacterial population
NASA Astrophysics Data System (ADS)
Chaudhuri, Indranath; Bose, Indrani
1999-08-01
Recently, Lenski et al. have carried out an experiment on bacterial evolution. Their findings support the theory of punctuated equilibrium in biological evolution. We show that the M=2 Bak-Sneppen model can explain some of the experimental results in a qualitative manner.
Payload specialists Patrick Baudry conducts equilibrium experiments
NASA Technical Reports Server (NTRS)
1985-01-01
Payload specialists Patrick Baudry participates in an experiment involving equilibrium and vertigo. He is anchored to the orbiter floor by foot restraints and is wearing a device over his eyes to measure angular head movement and up and down eye movement.
Equilibrium thermodynamics in modified gravitational theories
NASA Astrophysics Data System (ADS)
Bamba, Kazuharu; Geng, Chao-Qiang; Tsujikawa, Shinji
2010-04-01
We show that it is possible to obtain a picture of equilibrium thermodynamics on the apparent horizon in the expanding cosmological background for a wide class of modified gravity theories with the Lagrangian density f(R,ϕ,X), where R is the Ricci scalar and X is the kinetic energy of a scalar field ϕ. This comes from a suitable definition of an energy-momentum tensor of the “dark” component that respects to a local energy conservation in the Jordan frame. In this framework the horizon entropy S corresponding to equilibrium thermodynamics is equal to a quarter of the horizon area A in units of gravitational constant G, as in Einstein gravity. For a flat cosmological background with a decreasing Hubble parameter, S globally increases with time, as it happens for viable f(R) inflation and dark energy models. We also show that the equilibrium description in terms of the horizon entropy S is convenient because it takes into account the contribution of both the horizon entropy S' in non-equilibrium thermodynamics and an entropy production term.
Calculating Shocks In Flows At Chemical Equilibrium
NASA Technical Reports Server (NTRS)
Eberhardt, Scott; Palmer, Grant
1988-01-01
Boundary conditions prove critical. Conference paper describes algorithm for calculation of shocks in hypersonic flows of gases at chemical equilibrium. Although algorithm represents intermediate stage in development of reliable, accurate computer code for two-dimensional flow, research leading up to it contributes to understanding of what is needed to complete task.
Teaching Chemical Equilibrium with the Jigsaw Technique
ERIC Educational Resources Information Center
Doymus, Kemal
2008-01-01
This study investigates the effect of cooperative learning (jigsaw) versus individual learning methods on students' understanding of chemical equilibrium in a first-year general chemistry course. This study was carried out in two different classes in the department of primary science education during the 2005-2006 academic year. One of the classes…
A Progression of Static Equilibrium Laboratory Exercises
ERIC Educational Resources Information Center
Kutzner, Mickey; Kutzner, Andrew
2013-01-01
Although simple architectural structures like bridges, catwalks, cantilevers, and Stonehenge have been integral in human societies for millennia, as have levers and other simple tools, modern students of introductory physics continue to grapple with Newton's conditions for static equilibrium. As formulated in typical introductory physics…
Equilibrium rotation in field-reversed configurations
Steinhauer, Loren
2008-01-15
The turbulence that drives anomalous transport in field-reversed configurations (FRCs) is believed to break the otherwise closed magnetic surfaces inside the separatrix. This places electrons in the core of the plasma in electrical contact with those in the periphery. This effect was proposed and investigated in the context of spheromaks [D. D. Ryutov, Phys. Plasmas 14, 022506 (2007)]. The opening up of internal magnetic field lines serves to regulate the electrostatic potential in the interior of the plasma, and in turn drives ion rotation. In effect, 'end-shorting', a well-known phenomenon in the FRC scrape-off layer, also extends into the plasma interior. For conditions relevant to experiments, the ion rotation can be expressed in terms of equilibrium properties (density and temperature gradients) and as such is the 'equilibrium' rotation. This theory is incomplete in that it neglects evolving, transport-related effects that modify the equilibrium and, indirectly, the rotation rate. Consequently, the equilibrium rotation theory is only partially successful in predicting experimental results: although it predicts the average rotation well, the estimated degree of rotational shear seems unlikely, especially at late times in the plasma lifetime.
Equilibrium free energies from nonequilibrium processes
Jarzynski, C.
1997-10-29
A recent result, relating the (irreversible) work performed on a system during a non quasistatic process, to the Helmholtz free energy difference between two equilibrium states of the system, is discussed. A proof of this result is given for the special case when the evolution of the system in question is modeled by a Langevin equation in configuration space.
Conditions for the Existence of Market Equilibrium.
ERIC Educational Resources Information Center
Bryant, William D. A.
1997-01-01
Maintains that most graduate-level economics textbooks rarely mention the need for consumers to be above their minimum wealth position as a condition for market equilibrium. Argues that this omission leaves students with a mistaken sense about the range of circumstances under which market equilibria can exist. (MJP)
General Equilibrium Models: Improving the Microeconomics Classroom
ERIC Educational Resources Information Center
Nicholson, Walter; Westhoff, Frank
2009-01-01
General equilibrium models now play important roles in many fields of economics including tax policy, environmental regulation, international trade, and economic development. The intermediate microeconomics classroom has not kept pace with these trends, however. Microeconomics textbooks primarily focus on the insights that can be drawn from the…
The 'Schwarzschild-Kerr' Equilibrium Configurations
Manko, V. S.; Ruiz, E.
2010-12-07
We discuss the possibility of equilibrium between a Schwarzschild black hole possessing zero intrinsic angular momentum and a hyperextreme Kerr source. The balance occurs due to frame-dragging exerted by the latter source on the black-hole constituent, thus giving rise to a non-zero horizon's angular velocity parallel to the angular momentum of the Kerr object.
Generalized convective quasi-equilibrium principle
NASA Astrophysics Data System (ADS)
Yano, Jun-Ichi; Plant, Robert S.
2016-03-01
A generalization of Arakawa and Schubert's convective quasi-equilibrium principle is presented for a closure formulation of mass-flux convection parameterization. The original principle is based on the budget of the cloud work function. This principle is generalized by considering the budget for a vertical integral of an arbitrary convection-related quantity. The closure formulation includes Arakawa and Schubert's quasi-equilibrium, as well as both CAPE and moisture closures as special cases. The formulation also includes new possibilities for considering vertical integrals that are dependent on convective-scale variables, such as the moisture within convection. The generalized convective quasi-equilibrium is defined by a balance between large-scale forcing and convective response for a given vertically-integrated quantity. The latter takes the form of a convolution of a kernel matrix and a mass-flux spectrum, as in the original convective quasi-equilibrium. The kernel reduces to a scalar when either a bulk formulation is adopted, or only large-scale variables are considered within the vertical integral. Various physical implications of the generalized closure are discussed. These include the possibility that precipitation might be considered as a potentially-significant contribution to the large-scale forcing. Two dicta are proposed as guiding physical principles for the specifying a suitable vertically-integrated quantity.
Spontaneity and Equilibrium II: Multireaction Systems
ERIC Educational Resources Information Center
Raff, Lionel M.
2014-01-01
The thermodynamic criteria for spontaneity and equilibrium in multireaction systems are developed and discussed. When N reactions are occurring simultaneously, it is shown that G and A will depend upon N independent reaction coordinates, ?a (a = 1,2, ..., N), in addition to T and p for G or T and V for A. The general criteria for spontaneity and…
Assessing Students' Conceptual Understanding of Solubility Equilibrium.
ERIC Educational Resources Information Center
Raviolo, Andres
2001-01-01
Presents a problem on solubility equilibrium which involves macroscopic, microscopic, and symbolic levels of representation as a resource for the evaluation of students, and allows for assessment as to whether students have acquired an adequate conceptual understanding of the phenomenon. Also diagnoses difficulties with regard to previous…
Competitive Equilibrium and Classroom Pit Markets.
ERIC Educational Resources Information Center
Ruffle, Bradley J.
2003-01-01
Describes a pit-market experiment using the work of Charles A. Holt to illustrate to students the real world relevance of the competitive equilibrium concept. Explains how to set up and conduct a pit-market experiment, discusses features of the data, and provides accompanying materials. (JEH)
Chemical Equilibrium Composition of Aqueous Systems
1996-12-30
MINEQL is a subroutine package to calculate equilibrium composition of an aqueous system, accounting for mass transfer. MINEQL-EIR contains an additional base on enthalpy and heat capacity data and has the option to do calculations at temperatures different from 25 degrees C.
Effective equilibrium theory of nonequilibrium quantum transport
NASA Astrophysics Data System (ADS)
Dutt, Prasenjit; Koch, Jens; Han, Jong; Le Hur, Karyn
2011-12-01
The theoretical description of strongly correlated quantum systems out of equilibrium presents several challenges and a number of open questions persist. Here, we focus on nonlinear electronic transport through an interacting quantum dot maintained at finite bias using a concept introduced by Hershfield [S. Hershfield, Phys. Rev. Lett. 70 2134 (1993)] whereby one can express such nonequilibrium quantum impurity models in terms of the system's Lippmann-Schwinger operators. These scattering operators allow one to reformulate the nonequilibrium problem as an effective equilibrium problem associated with a modified Hamiltonian. In this paper, we provide a pedagogical analysis of the core concepts of the effective equilibrium theory. First, we demonstrate the equivalence between observables computed using the Schwinger-Keldysh framework and the effective equilibrium approach, and relate Green's functions in the two theoretical frameworks. Second, we expound some applications of this method in the context of interacting quantum impurity models. We introduce a novel framework to treat effects of interactions perturbatively while capturing the entire dependence on the bias voltage. For the sake of concreteness, we employ the Anderson model as a prototype for this scheme. Working at the particle-hole symmetric point, we investigate the fate of the Abrikosov-Suhl resonance as a function of bias voltage and magnetic field.
Equilibrium Molecular Thermodynamics from Kirkwood Sampling
2015-01-01
We present two methods for barrierless equilibrium sampling of molecular systems based on the recently proposed Kirkwood method (J. Chem. Phys.2009, 130, 134102). Kirkwood sampling employs low-order correlations among internal coordinates of a molecule for random (or non-Markovian) sampling of the high dimensional conformational space. This is a geometrical sampling method independent of the potential energy surface. The first method is a variant of biased Monte Carlo, where Kirkwood sampling is used for generating trial Monte Carlo moves. Using this method, equilibrium distributions corresponding to different temperatures and potential energy functions can be generated from a given set of low-order correlations. Since Kirkwood samples are generated independently, this method is ideally suited for massively parallel distributed computing. The second approach is a variant of reservoir replica exchange, where Kirkwood sampling is used to construct a reservoir of conformations, which exchanges conformations with the replicas performing equilibrium sampling corresponding to different thermodynamic states. Coupling with the Kirkwood reservoir enhances sampling by facilitating global jumps in the conformational space. The efficiency of both methods depends on the overlap of the Kirkwood distribution with the target equilibrium distribution. We present proof-of-concept results for a model nine-atom linear molecule and alanine dipeptide. PMID:25915525
Technology Solutions Case Study: Preventing Thermal Bypass
none,
2012-10-01
This project highlights the importance of continuous air barriers in full alignment with insulation to prevent thermal bypasses and achieve high energy performance, and recommends use of ENERGY STAR's Thermal Bypass Inspection Checklist.
Equilibrium and off-equilibrium trap-size scaling in one-dimensional ultracold bosonic gases
Campostrini, Massimo; Vicari, Ettore
2010-12-15
We study some aspects of equilibrium and off-equilibrium quantum dynamics of dilute bosonic gases in the presence of a trapping potential. We consider systems with a fixed number of particles and study their scaling behavior with increasing the trap size. We focus on one-dimensional bosonic systems, such as gases described by the Lieb-Liniger model and its Tonks-Girardeau limit of impenetrable bosons, and gases constrained in optical lattices as described by the Bose-Hubbard model. We study their quantum (zero-temperature) behavior at equilibrium and off equilibrium during the unitary time evolution arising from changes of the trapping potential, which may be instantaneous or described by a power-law time dependence, starting from the equilibrium ground state for an initial trap size. Renormalization-group scaling arguments and analytical and numerical calculations show that the trap-size dependence of the equilibrium and off-equilibrium dynamics can be cast in the form of a trap-size scaling in the low-density regime, characterized by universal power laws of the trap size, in dilute gases with repulsive contact interactions and lattice systems described by the Bose-Hubbard model. The scaling functions corresponding to several physically interesting observables are computed. Our results are of experimental relevance for systems of cold atomic gases trapped by tunable confining potentials.
Aines, Roger D.; Newmark, Robin L.; Knauss, Kevin G.
2000-01-01
A thermal treatment wall emplaced to perform in-situ destruction of contaminants in groundwater. Thermal destruction of specific contaminants occurs by hydrous pyrolysis/oxidation at temperatures achievable by existing thermal remediation techniques (electrical heating or steam injection) in the presence of oxygen or soil mineral oxidants, such as MnO.sub.2. The thermal treatment wall can be installed in a variety of configurations depending on the specific objectives, and can be used for groundwater cleanup, wherein in-situ destruction of contaminants is carried out rather than extracting contaminated fluids to the surface, where they are to be cleaned. In addition, the thermal treatment wall can be used for both plume interdiction and near-wellhead in-situ groundwater treatment. Thus, this technique can be utilized for a variety of groundwater contamination problems.
Explorations in achievement motivation
NASA Technical Reports Server (NTRS)
Helmreich, Robert L.
1982-01-01
Recent research on the nature of achievement motivation is reviewed. A three-factor model of intrinsic motives is presented and related to various criteria of performance, job satisfaction and leisure activities. The relationships between intrinsic and extrinsic motives are discussed. Needed areas for future research are described.
Achieving health care affordability.
Payson, Norman C
2002-10-01
Not all plans are jumping headlong into the consumer-centric arena. In this article, the CEO of Oxford Health Plans discusses how advanced managed care can achieve what other consumer-centric programs seek to do--provide affordable, quality health care. PMID:12391815
Issues in Achievement Testing.
ERIC Educational Resources Information Center
Baker, Eva L.
This booklet is intended to help school personnel, parents, students, and members of the community understand concepts and research relating to achievement testing in public schools. The paper's sections include: (1) test use with direct effects on students (test of certification, selection, and placement); (2) test use with indirect effects on…
Achieving Peace through Education.
ERIC Educational Resources Information Center
Clarken, Rodney H.
While it is generally agreed that peace is desirable, there are barriers to achieving a peaceful world. These barriers are classified into three major areas: (1) an erroneous view of human nature; (2) injustice; and (3) fear of world unity. In a discussion of these barriers, it is noted that although the consciousness and conscience of the world…
ERIC Educational Resources Information Center
Hartley, Tricia
2009-01-01
National learning and skills policy aims both to build economic prosperity and to achieve social justice. Participation in higher education (HE) has the potential to contribute substantially to both aims. That is why the Campaign for Learning has supported the ambition to increase the proportion of the working-age population with a Level 4…
Intelligence and Educational Achievement
ERIC Educational Resources Information Center
Deary, Ian J.; Strand, Steve; Smith, Pauline; Fernandes, Cres
2007-01-01
This 5-year prospective longitudinal study of 70,000+ English children examined the association between psychometric intelligence at age 11 years and educational achievement in national examinations in 25 academic subjects at age 16. The correlation between a latent intelligence trait (Spearman's "g"from CAT2E) and a latent trait of educational…
SALT and Spelling Achievement.
ERIC Educational Resources Information Center
Nelson, Joan
A study investigated the effects of suggestopedic accelerative learning and teaching (SALT) on the spelling achievement, attitudes toward school, and memory skills of fourth-grade students. Subjects were 20 male and 28 female students from two self-contained classrooms at Kennedy Elementary School in Rexburg, Idaho. The control classroom and the…
ERIC Educational Resources Information Center
Bracey, Gerald W.
2008-01-01
In his "Wall Street Journal" op-ed on the 25th of anniversary of "A Nation At Risk", former assistant secretary of education Chester E. Finn Jr. applauded the report for turning U.S. education away from equality and toward achievement. It was not surprising, then, that in mid-2008, Finn arranged a conference to examine the potential "Robin Hood…
INTELLIGENCE, PERSONALITY AND ACHIEVEMENT.
ERIC Educational Resources Information Center
MUIR, R.C.; AND OTHERS
A LONGITUDINAL DEVELOPMENTAL STUDY OF A GROUP OF MIDDLE CLASS CHILDREN IS DESCRIBED, WITH EMPHASIS ON A SEGMENT OF THE RESEARCH INVESTIGATING THE RELATIONSHIP OF ACHIEVEMENT, INTELLIGENCE, AND EMOTIONAL DISTURBANCE. THE SUBJECTS WERE 105 CHILDREN AGED FIVE TO 6.3 ATTENDING TWO SCHOOLS IN MONTREAL. EACH CHILD WAS ASSESSED IN THE AREAS OF…
School Students' Science Achievement
ERIC Educational Resources Information Center
Shymansky, James; Wang, Tzu-Ling; Annetta, Leonard; Everett, Susan; Yore, Larry D.
2013-01-01
This paper is a report of the impact of an externally funded, multiyear systemic reform project on students' science achievement on a modified version of the Third International Mathematics and Science Study (TIMSS) test in 33 small, rural school districts in two Midwest states. The systemic reform effort utilized a cascading leadership strategy…
ERIC Educational Resources Information Center
Walberg, Herbert J.
2010-01-01
For the last half century, higher spending and many modern reforms have failed to raise the achievement of students in the United States to the levels of other economically advanced countries. A possible explanation, says Herbert Walberg, is that much current education theory is ill informed about scientific psychology, often drawing on fads and…
Essays on Educational Achievement
ERIC Educational Resources Information Center
Ampaabeng, Samuel Kofi
2013-01-01
This dissertation examines the determinants of student outcomes--achievement, attainment, occupational choices and earnings--in three different contexts. The first two chapters focus on Ghana while the final chapter focuses on the US state of Massachusetts. In the first chapter, I exploit the incidence of famine and malnutrition that resulted to…
Increasing Male Academic Achievement
ERIC Educational Resources Information Center
Jackson, Barbara Talbert
2008-01-01
The No Child Left Behind legislation has brought greater attention to the academic performance of American youth. Its emphasis on student achievement requires a closer analysis of assessment data by school districts. To address the findings, educators must seek strategies to remedy failing results. In a mid-Atlantic district of the Unites States,…
Setting and Achieving Objectives.
ERIC Educational Resources Information Center
Knoop, Robert
1986-01-01
Provides basic guidelines which school officials and school boards may find helpful in negotiating, establishing, and managing objectives. Discusses characteristics of good objectives, specific and directional objectives, multiple objectives, participation in setting objectives, feedback on goal process and achievement, and managing a school…
Schools Achieving Gender Equity.
ERIC Educational Resources Information Center
Revis, Emma
This guide is designed to assist teachers presenting the Schools Achieving Gender Equity (SAGE) curriculum for vocational education students, which was developed to align gender equity concepts with the Kentucky Education Reform Act (KERA). Included in the guide are lesson plans for classes on the following topics: legal issues of gender equity,…
ERIC Educational Resources Information Center
Ohrn, Deborah Gore, Ed.
1993-01-01
This issue of the Goldfinch highlights some of Iowa's 20th century women of achievement. These women have devoted their lives to working for human rights, education, equality, and individual rights. They come from the worlds of politics, art, music, education, sports, business, entertainment, and social work. They represent Native Americans,…
ERIC Educational Resources Information Center
Goodwin, MacArthur
2000-01-01
Focuses on policy issues that have affected arts education in the twentieth century, such as: interest in discipline-based arts education, influence of national arts associations, and national standards and coordinated assessment. States that whether the policy decisions are viewed as achievements or disasters are for future determination. (CMK)
ERIC Educational Resources Information Center
Prince George's Community Coll., Largo, MD. Office of Institutional Research and Analysis.
This report summarizes the achievements of Prince George's Community College (PGCC) with regard to minority outcomes. Table 1 summarizes the undergraduate enrollment trends for African Americans as well as total minorities from fall 1994 through fall 1998. Both the headcount number of African American students and the proportion of African…