Equilibrium contact angle or the most-stable contact angle?
Montes Ruiz-Cabello, F J; Rodríguez-Valverde, M A; Cabrerizo-Vílchez, M A
2014-04-01
It is well-established that the equilibrium contact angle in a thermodynamic framework is an "unattainable" contact angle. Instead, the most-stable contact angle obtained from mechanical stimuli of the system is indeed experimentally accessible. Monitoring the susceptibility of a sessile drop to a mechanical stimulus enables to identify the most stable drop configuration within the practical range of contact angle hysteresis. Two different stimuli may be used with sessile drops: mechanical vibration and tilting. The most stable drop against vibration should reveal the changeless contact angle but against the gravity force, it should reveal the highest resistance to slide down. After the corresponding mechanical stimulus, once the excited drop configuration is examined, the focus will be on the contact angle of the initial drop configuration. This methodology needs to map significantly the static drop configurations with different stable contact angles. The most-stable contact angle, together with the advancing and receding contact angles, completes the description of physically realizable configurations of a solid-liquid system. Since the most-stable contact angle is energetically significant, it may be used in the Wenzel, Cassie or Cassie-Baxter equations accordingly or for the surface energy evaluation.
Nematic-like stable glasses without equilibrium liquid crystal phases.
Gómez, Jaritza; Gujral, Ankit; Huang, Chengbin; Bishop, Camille; Yu, Lian; Ediger, M D
2017-02-07
We report the thermal and structural properties of glasses of posaconazole, a rod-like molecule, prepared using physical vapor deposition (PVD). PVD glasses of posaconazole can show substantial molecular orientation depending upon the choice of substrate temperature, Tsubstrate, during deposition. Ellipsometry and IR measurements indicate that glasses prepared at Tsubstrate very near the glass transition temperature (Tg) are highly ordered. For these posaconazole glasses, the orientation order parameter is similar to that observed in macroscopically aligned nematic liquid crystals, indicating that the molecules are mostly parallel to one another and perpendicular to the interface. To our knowledge, these are the most anisotropic glasses ever prepared by PVD from a molecule that does not form equilibrium liquid crystal phases. These results are consistent with a previously proposed mechanism in which molecular orientation in PVD glasses is inherited from the orientation present at the free surface of the equilibrium liquid. This mechanism suggests that molecular orientation at the surface of the equilibrium liquid of posaconazole is nematic-like. Posaconazole glasses can show very high kinetic stability; the isothermal transformation of a 400 nm glass into the supercooled liquid occurs via a propagating front that originates at the free surface and requires ∼10(5) times the structural relaxation time of the liquid (τα). We also studied the kinetic stability of PVD glasses of itraconazole, which is a structurally similar molecule with equilibrium liquid crystal phases. While itraconazole glasses can be even more anisotropic than posaconazole glasses, they exhibit lower kinetic stability.
Nematic-like stable glasses without equilibrium liquid crystal phases
NASA Astrophysics Data System (ADS)
Gómez, Jaritza; Gujral, Ankit; Huang, Chengbin; Bishop, Camille; Yu, Lian; Ediger, M. D.
2017-02-01
We report the thermal and structural properties of glasses of posaconazole, a rod-like molecule, prepared using physical vapor deposition (PVD). PVD glasses of posaconazole can show substantial molecular orientation depending upon the choice of substrate temperature, Tsubstrate, during deposition. Ellipsometry and IR measurements indicate that glasses prepared at Tsubstrate very near the glass transition temperature (Tg) are highly ordered. For these posaconazole glasses, the orientation order parameter is similar to that observed in macroscopically aligned nematic liquid crystals, indicating that the molecules are mostly parallel to one another and perpendicular to the interface. To our knowledge, these are the most anisotropic glasses ever prepared by PVD from a molecule that does not form equilibrium liquid crystal phases. These results are consistent with a previously proposed mechanism in which molecular orientation in PVD glasses is inherited from the orientation present at the free surface of the equilibrium liquid. This mechanism suggests that molecular orientation at the surface of the equilibrium liquid of posaconazole is nematic-like. Posaconazole glasses can show very high kinetic stability; the isothermal transformation of a 400 nm glass into the supercooled liquid occurs via a propagating front that originates at the free surface and requires ˜105 times the structural relaxation time of the liquid (τα). We also studied the kinetic stability of PVD glasses of itraconazole, which is a structurally similar molecule with equilibrium liquid crystal phases. While itraconazole glasses can be even more anisotropic than posaconazole glasses, they exhibit lower kinetic stability.
Study on stable equilibrium of levitated impeller in rotary pump with passive magnetic bearings.
Qian, K X; Wan, F K; Ru, W M; Zeng, P; Yuan, H Y
2006-01-01
It is widely acknowledged that the permanent maglev cannot achieve stable equilibrium; the authors have developed, however, a stable permanent maglev centrifugal blood pump. Permanent maglev needs no position detection and feedback control of the rotor, nevertheless the eccentric distance (ED) and vibration amplitude (VA) of the levitator have been measured to demonstrate the levitation and to investigate the factors affecting levitation. Permanent maglev centrifugal impeller pump has a rotor and a stator. The rotor is driven by stator coil and levitated by two passive magnetic bearings. The rotor position is measured by four Hall sensors, which are distributed evenly and peripherally on the end of the stator against the magnetic ring of the bearing on the rotor. The voltage differences of the sensors due to different distances between the sensors and the magnetic ring are converted into ED. The results verify that the rotor can be disaffiliated from the stator if the rotating speed and the flow rate of the pump are large enough, that is, the maximal ED will reduce to about half of the gap between the rotor and the stator. In addition, the gap between rotor and stator and the viscosity of the fluid to be pumped also affect levitation. The former has an optimal value of approximately 2% of the radius of the rotor. For the latter, levitation stability is better with higher viscosity, meaning smaller ED and VA. The pressure to be pumped has no effect on levitation.
On Nash Equilibrium and Evolutionarily Stable States That Are Not Characterised by the Folk Theorem.
Li, Jiawei; Kendall, Graham
2015-01-01
In evolutionary game theory, evolutionarily stable states are characterised by the folk theorem because exact solutions to the replicator equation are difficult to obtain. It is generally assumed that the folk theorem, which is the fundamental theory for non-cooperative games, defines all Nash equilibria in infinitely repeated games. Here, we prove that Nash equilibria that are not characterised by the folk theorem do exist. By adopting specific reactive strategies, a group of players can be better off by coordinating their actions in repeated games. We call it a type-k equilibrium when a group of k players coordinate their actions and they have no incentive to deviate from their strategies simultaneously. The existence and stability of the type-k equilibrium in general games is discussed. This study shows that the sets of Nash equilibria and evolutionarily stable states have greater cardinality than classic game theory has predicted in many repeated games.
Stable Equilibrium Based on Lévy Statistics:A Linear Boltzmann Equation Approach
NASA Astrophysics Data System (ADS)
Barkai, Eli
2004-06-01
To obtain further insight on possible power law generalizations of Boltzmann equilibrium concepts, we consider stochastic collision models. The models are a generalization of the Rayleigh collision model, for a heavy one dimensional particle M interacting with ideal gas particles with a mass m<< M. Similar to previous approaches we assume elastic, uncorrelated, and impulsive collisions. We let the bath particle velocity distribution function to be of general form, namely we do not postulate a specific form of power-law equilibrium. We show, under certain conditions, that the velocity distribution function of the heavy particle is Lévy stable, the Maxwellian distribution being a special case. We demonstrate our results with numerical examples. The relation of the power law equilibrium obtained here to thermodynamics is discussed. In particular we compare between two models: a thermodynamic and an energy scaling approaches. These models yield insight into questions like the meaning of temperature for power law equilibrium, and into the issue of the universality of the equilibrium (i.e., is the width of the generalized Maxwellian distribution functions obtained here, independent of coupling constant to the bath).
Techniques for achieving thermal equilibrium in molecular dynamics calculations for solids
NASA Astrophysics Data System (ADS)
Wu, Ernest Yue; Friauf, Robert J.
1990-06-01
We develop techniques for achieving thermal equilibrium in molecular dynamics calculations for solids. Atoms in a Lennard-Jones solid are initially given random velocities and displacements from their equilibrium positions with suitably scaled Maxwellian distributions. A quantitative criterion for thermal equilibrium of the solid is established by using the equipartition of energy theorem. At high temperatures, thermal expansion is studied, and we introduce a method for adjusting the lattice parameter to ensure zero external pressure. The results of molecular dynamics simulations show agreement with experimental data for rare gas and ionic crystals.
A long-term stable equilibrium for synchronous binaries including tides and the byorp effect
NASA Astrophysics Data System (ADS)
Jacobson, Seth A.; Scheeres, D. J.
2011-04-01
We present theoretical evidence for the existence of a long-term stable equilibrium solution for synchronous binary asteroids accounting for mutual body tides, the binary YORP (BYORP) effect and dynamics. Synchronous binary asteroid systems consist of a rapidly spinning primary and a tidally-locked secondary, analogous to the Earth-Moon system. Tidal evolution of these systems leads to growth in the semi-major axis. Evolution from the BYORP effect can lead to both contraction and growth of the semi-major axis. There are two scenarios for joint evolution of a synchronous binary when both effects are considered: expansive and opposing evolution. During joint expansive evolution, both effects grow the semi-major axis. The system will either grow to the Hill sphere and disrupt if tidally dominated, or the mutual orbit will be de-stabilized due to runaway eccentricity growth if BYORP dominated. During joint opposing evolution, tidal and BYORP evolution act to evolve the system to a stable equilibrium. The location of this equilibrium to first order depends on just the tidal parameters, specific tidal dissipation number Q and the tidal Love number k, as well as the BYORP shape coefficient. If the observed population of small (0.1 - 10 km diameter), synchronous binaries are assumed to be in this static configuration, then our analysis shows that a monolithic geophysical model is not satisfactory, whereas the ``rubble pile'' model proposed by Goldreich & Sari (2009) is sufficient to prevent runaway eccentricity growth. The existence of this equilibrium and a secondary shape model built from observations enables direct study of asteroid geophysics through tidal theory. The existence of this equilibrium would be confirmed by a lack of migration in observational tests for the BYORP effect. Goldreich, P. & R. Sari, ApJ, 691:54-60 (2009)
Student Misconceptions in Chemical Equilibrium as Related to Cognitive Level and Achievement.
ERIC Educational Resources Information Center
Wheeler, Alan E.; Kass, Heidi
Reported is an investigation to determine the nature and extent of student misconceptions in chemical equilibrium and to ascertain the degree to which certain misconceptions are related to chemistry achievement and to performance on specific tasks involving cognitive transformations characteristic of the concrete and formal operational stages of…
Stapley, P; Pozzo, T
1998-01-01
In normal gravity conditions the execution of voluntary movement involves the displacement of body segments as well as the maintenance of a stable reference value for equilibrium control. It has been suggested that centre of mass (CM) projection within the supporting base (BS) is the stabilised reference for voluntary action, and is conserved in weightlessness. The purpose of this study was to determine if the CM is stabilised during whole body reaching movements executed in weightlessness. The reaching task was conducted by two cosmonauts aboard the Russian orbital station MIR, during the Franco-Russian mission ALTAIR, 1993. Movements of reflective markers were recorded using a videocamera, successive images being reconstructed by computer every 40ms. The position of the CM, ankle joint torques and shank and thigh angles were computed for each subject pre- in- and post-flight using a 7-link mathematical model. Results showed that both cosmonauts adopted a backward leaning posture prior to reaching movements. Inflight, the CM was displaced throughout values in the horizontal axis three times those of pre-flight measures. In addition, ankle dorsi flexor torques inflight increased to values double those of pre- and post-flight tests. This study concluded that CM displacements do not remain stable during complex postural equilibrium tasks executed in weightlessness. Furthermore, in the absence of gravity, subjects changed their strategy for producing ankle torque during spaceflight from a forward to a backward leaning posture.
NASA Astrophysics Data System (ADS)
Stapley, Paul; Pozzo, Thierry
In normal gravity conditions the execution of voluntary movement involves the displacement of body segments as well as the maintenance of a stable reference value for equilibrium control. It has been suggested that centre of mass (CM) projection within the supporting base (BS) is the stabilised reference for voluntary action, and is conserved in weightlessness. The purpose of this study was to determine if the CM is stabilised during whole body reaching movements executed in weightlessness. The reaching task was conducted by two cosmonauts aboard the Russian orbital station MIR, during the Franco-Russian mission ALTAIR, 1993. Movements of reflective markers were recorded using a videocamera, successive images being reconstructed by computer every 40ms. The position of the CM, ankle joint torques and shank and thigh angles were computed for each subject pre- in- and post-flight using a 7-link mathematical model. Results showed that both cosmonauts adopted a backward leaning posture prior to reaching movements. Inflight, the CM was displaced throughout values in the horizontal axis three times those of pre-flight measures. In addition, ankle dorsi flexor torques inflight increased to values double those of pre- and post-flight tests. This study concluded that CM displacements do not remain stable during complex postural equilibrium tasks executed in weightlessness. Furthermore, in the absence of gravity, subjects changed their strategy for producing ankle torque during spaceflight from a forward to a backward leaning posture.
Anammox-zeolite system acting as buffer to achieve stable effluent nitrogen values.
Yapsakli, Kozet; Aktan, Cigdem Kalkan; Mertoglu, Bulent
2017-02-01
For a successful nitrogen removal, Anammox process needs to be established in line with a stable partial nitritation pretreatment unit since wastewater influent is mostly unsuitable for direct treatment by Anammox. Partial nitritation is, however, a critical bottleneck for the nitrogen removal since it is often difficult to maintain the right proportions of NO2-N and NH4-N during long periods of time for Anammox process. This study investigated the potential of Anammox-zeolite biofilter to buffer inequalities in nitrite and ammonium nitrogen in the influent feed. Anammox-zeolite biofilter combines the ion-exchange property of zeolite with the biological removal by Anammox process. Continuous-flow biofilter was operated for 570 days to test the response of Anammox-zeolite system for irregular ammonium and nitrite nitrogen entries. The reactor demonstrated stable and high nitrogen removal efficiencies (approximately 95 %) even when the influent NO2-N to NH4-N ratios were far from the stoichiometric ratio for Anammox reaction (i.e. NO2-N to NH4-N ranging from 0 to infinity). This is achieved by the sorption of surplus NH4-N by zeolite particles in case ammonium rich influent came in excess with respect to Anammox stoichiometry. Similarly, when ammonium-poor influent is fed to the reactor, ammonium desorption took place due to shifts in ion-exchange equilibrium and deficient amount were supplied by previously sorbed NH4-N. Here, zeolite acted as a preserving reservoir of ammonium where both sorption and desorption took place when needed and this caused the Anammox-zeolite system to act as a buffer system to generate a stable effluent.
NASA Astrophysics Data System (ADS)
Black, Jay R.; Kavner, Abby; Schauble, Edwin A.
2011-02-01
The goal of this study is to determine reduced partition function ratios for a variety of species of zinc, both as a metal and in aqueous solutions in order to calculate equilibrium stable isotope partitioning. We present calculations of the magnitude of Zn stable-isotope fractionation ( 66,67,68Zn/ 64Zn) between aqueous species and metallic zinc using measured vibrational spectra (fit from neutron scattering studies of metallic zinc) and a variety of electronic structure models. The results show that the reduced metal, Zn(0), will be light in equilibrium with oxidized Zn(II) aqueous species, with the best estimates for the Zn(II)-Zn(0) fractionation between hexaquo species and metallic zinc being Δ 66/64Zn aq-metal ˜ 1.6‰ at 25 °C, and Δ 66/64Zn aq-metal ˜ 0.8‰ between the tetrachloro zinc complex and metallic zinc at 25 °C using B3LYP/aug-cc-pVDZ level of theory and basis set. To examine the behavior of zinc in various aqueous solution chemistries, models for Zn(II) complex speciation were used to determine which species are thermodynamically favorable and abundant under a variety of different conditions relevant to natural waters, experimental and industrial solutions. The optimal molecular geometries for [Zn(H 2O) 6] 2+, [Zn(H 2O) 6]·SO 4, [ZnCl 4] 2- and [Zn(H 2O) 3(C 3H 5O(COO) 3)] - complexes in various states of solvation, protonation and coordination were calculated at various levels of electronic structure theory and basis set size. Isotopic reduced partition function ratios were calculated from frequency analyses of these optimized structures. Increasing the basis set size typically led to a decrease in the calculated reduced partition function ratios of ˜0.5‰ with values approaching a plateau using the aug-cc-pVDZ basis set or larger. The widest range of species were studied at the B3LYP/LAN2DZ/6-31G ∗ level of theory and basis-set size for comparison. Aqueous zinc complexes where oxygen is bound to the metal center tended to have the
Tremblay, Raymond L.; Raventos, Josep; Ackerman, James D.
2015-01-01
Background and Aims Evaluation of population projection matrices (PPMs) that are focused on asymptotically based properties of populations is a commonly used approach to evaluate projected dynamics of managed populations. Recently, a set of tools for evaluating the properties of transient dynamics has been expanded to evaluate PPMs and to consider the dynamics of populations prior to attaining the stable-stage distribution, a state that may never be achieved in disturbed or otherwise ephemeral habitats or persistently small populations. This study re-evaluates data for a tropical orchid and examines the value of including such analyses in an integrative approach. Methods Six small populations of Lepanthes rubripetala were used as a model system and the R software package popdemo was used to produce estimates of the indices for the asymptotic growth rate (lambda), sensitivities, reactivity, first-time step attenuation, maximum amplification, maximum attenuation, maximal inertia and maximal attenuation. The response in lambda to perturbations of demographic parameters using transfer functions and multiple perturbations on growth, stasis and fecundity were also determined. The results were compared with previously published asymptotic indices. Key Results It was found that combining asymptotic and transient dynamics expands the understanding of possible population changes. Comparison of the predicted density from reactivity and first-time step attenuation with the observed change in population size in two orchid populations showed that the observed density was within the predicted range. However, transfer function analysis suggests that the traditional approach of measuring perturbation of growth rates and persistence (inertia) may be misleading and is likely to result in erroneous management decisions. Conclusions Based on the results, an integrative approach is recommended using traditional PPMs (asymptotic processes) with an evaluation of the diversity of dynamics
Turbulent relaxation and meta-stable equilibrium states of an electron plasma
NASA Astrophysics Data System (ADS)
Rodgers, Douglas J.
A Malmberg-Penning electron trap allows for the experimental study of nearly ideal, two-dimensional (2D) inviscid (Euler) hydrodynamics. This is perhaps the simplest case of self organizing nonlinear turbulence, and is therefore a paradigm for dynamo theory, Taylor relaxation, selective decay and other nonlinear fluid processes. The dynamical relaxation of a pure electron plasma in the guiding-center-drift approximation is studied, comparing experiments, numerical simulations and statistical theories of weakly-dissipative 2D turbulence. The nonuniform metastable equilibrium states resulting from turbulent evolution are examined, and are well-described by a maximum entropy principle for constrained circulation, energy, and angular momentum. The turbulent decay of the system is also examined, and a similarity decay law is proposed which incorporates the substantial enstrophy trapped in the metastable equilibrium. This law approaches Batchelor's t-2 self-similar decay in the limit of strong turbulence, and is verified in turbulent evolution in the electron plasma experiment.
Chaos control in a chaotic system with only one stable equilibrium point
NASA Astrophysics Data System (ADS)
Buscarino, Arturo; Fortuna, Luigi; Frasca, Mattia; Gambuzza, Lucia Valentina; Pham, Thanh Viet
2012-09-01
The recent finding on the effect of a small bias in Sprott-like systems, i.e., the stabilization of the unstable equilibrium point through the addition of a small bias [1], paves the way to efficient methods for chaos control in such systems. In this work, we investigate the control of one of such systems both in the ideal case of absence of noise and in the presence of noise. We then propose an experimental setup for the experimental verification of the introduced method.
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,…
Nuclear Volume Effects in Equilibrium Stable Isotope Fractionations of Hg, Tl and Pb Isotope Systems
NASA Astrophysics Data System (ADS)
Yang, S.; Liu, Y.
2014-12-01
Many evidences showed that heavy isotope systems could be significantly fractionated as the consequence of the nuclear volume effect (NVE) or so-called nuclear field shift effect. Here we investigate NVEs of Hg, Tl and Pb isotope systems by using quantum chemistry computational methods with careful evaluation on quantum relativistic effects via the Dirac's formalism of full-electron wavefunction. Our results generally agree with previous studies but with noticeable differences in many cases. With the unique NVE driving force, equilibrium 202Hg/198Hg and 205Tl/203Tl isotopes can be fractionated up to 3.94‰ and 2.78‰ at 0℃, respectively, showing potentially large equilibrium isotope fractionations can be expected for future studies of these two isotope systems. Moreover, the NVE causes large mass-independent fractionations (MIF) for odd-mass isotopes (e.g., ∆199NVHg and ∆201NVHg) and small MIFs for even-mass isotopes (e.g., ∆200NVHg). For Pb isotope system, NVEs induce isotope fractionations up to 1.62‰ (207Pb/206Pb) and 4.06‰ (208Pb/206Pb) at 0℃. However, contributions from classical mass-dependent driving force are small, about 0.1-0.5‰ for 207Pb/206Pb and 0.2-0.9‰ for 208Pb/206Pb. We find that Pb4+-bearing species can be significantly enriched heavy isotopes than Pb2+-bearing species. Comparing to Pb0, Pb2+-bearing species even enrich lighter Pb isotopes. A very strange and interesting thing is that the beta value of Pb2+-bearing species can be smaller than the unity (1.000). Similar thing has been found on Tl+-bearing species. This is an impossible and unexplained situation if only based on classical mass-dependent isotope fractionation theory (e.g., Bigeleisen-Mayer equation). The consequence is that the different direction of beta values of Pb2+-bearing species will let the Pb isotope fractionation even larger when they fractionate with Pb4+-bearing species. Moreover, NVEs also cause mass-independent fractionation (MIF) of odd 207Pb
Hsp70 chaperones are non-equilibrium machines that achieve ultra-affinity by energy consumption.
De Los Rios, Paolo; Barducci, Alessandro
2014-05-27
70-kDa Heat shock proteins are ATP-driven molecular chaperones that perform a myriad of essential cellular tasks. Although structural and biochemical studies have shed some light on their functional mechanism, the fundamental issue of the role of energy consumption, due to ATP-hydrolysis, has remained unaddressed. Here we establish a clear connection between the non-equilibrium nature of Hsp70, due to ATP hydrolysis, and the determining feature of its function, namely its high affinity for its substrates. Energy consumption can indeed decrease the dissociation constant of the chaperone-substrate complex by several orders of magnitude with respect to an equilibrium scenario. We find that the biochemical requirements for observing such ultra-affinity coincide with the physiological conditions in the cell. Our results rationalize several experimental observations and pave the way for further analysis of non-equilibrium effects underlying chaperone functions.DOI: http://dx.doi.org/10.7554/eLife.02218.001.
Nuclear volume effects in equilibrium stable isotope fractionations of mercury, thallium and lead
NASA Astrophysics Data System (ADS)
Yang, Sha; Liu, Yun
2015-07-01
The nuclear volume effects (NVEs) of Hg, Tl and Pb isotope systems are investigated with careful evaluation on quantum relativistic effects via the Dirac’s formalism of full-electron wave function. Equilibrium 202Hg/198Hg, 205Tl/203Tl, 207Pb/206Pb and 208Pb/206Pb isotope fractionations are found can be up to 3.61‰, 2.54‰, 1.48‰ and 3.72‰ at room temperature, respectively, larger than fractionations predicted by classical mass-dependent isotope fractionations theory. Moreover, the NVE can cause mass-independent fractionations (MIF) for odd-mass isotopes and even-mass isotopes. The plot of vs. for Hg-bearing species falls into a straight line with the slope of 1.66, which is close to previous experimental results. For the first time, Pb4+-bearing species are found can enrich heavier Pb isotopes than Pb2+-bearing species to a surprising extent, e.g., the enrichment can be up to 4.34‰ in terms of 208Pb/206Pb at room temperature, due to their NVEs are in opposite directions. In contrast, fractionations among Pb2+-bearing species are trivial. Therefore, the large Pb fractionation changes provide a potential new tracer for redox conditions in young and closed geologic systems. The magnitudes of NVE-driven even-mass MIFs of Pb isotopes (i.e., ) and odd-mass MIFs (i.e., ) are almost the same but with opposite signs.
Nuclear volume effects in equilibrium stable isotope fractionations of mercury, thallium and lead.
Yang, Sha; Liu, Yun
2015-07-30
The nuclear volume effects (NVEs) of Hg, Tl and Pb isotope systems are investigated with careful evaluation on quantum relativistic effects via the Dirac's formalism of full-electron wave function. Equilibrium (202)Hg/(198)Hg, (205)Tl/(203)Tl, (207)Pb/(206)Pb and (208)Pb/(206)Pb isotope fractionations are found can be up to 3.61‰, 2.54‰, 1.48‰ and 3.72‰ at room temperature, respectively, larger than fractionations predicted by classical mass-dependent isotope fractionations theory. Moreover, the NVE can cause mass-independent fractionations (MIF) for odd-mass isotopes and even-mass isotopes. The plot of [formula in text] for Hg-bearing species falls into a straight line with the slope of 1.66, which is close to previous experimental results. For the first time, Pb(4+)-bearing species are found can enrich heavier Pb isotopes than Pb(2+)-bearing species to a surprising extent, e.g., the enrichment can be up to 4.34‰ in terms of (208)Pb/(206)Pb at room temperature, due to their NVEs are in opposite directions. In contrast, fractionations among Pb(2+)-bearing species are trivial. Therefore, the large Pb fractionation changes provide a potential new tracer for redox conditions in young and closed geologic systems. The magnitudes of NVE-driven even-mass MIFs of Pb isotopes (i.e., [formula in text]) and odd-mass MIFs (i.e., [formula in text) are almost the same but with opposite signs.
Salzmann-Erikson, Martin; L Tz N, Kim; Ivarsson, Ann-Britt; Eriksson, Henrik
2011-01-01
This article presents intensive psychiatric nurses' work and nursing care. The aim of the study was to describe expressions of cultural knowing in nursing care in psychiatric intensive care units (PICU). Spradley's ethnographic methodology was applied. Six themes emerged as frames for nursing care in psychiatric intensive care: providing surveillance, soothing, being present, trading information, maintaining security and reducing. These themes are used to strike a balance between turbulence and stability and to achieve equilibrium. As the nursing care intervenes when turbulence emerges, the PICU becomes a sanctuary that offers tranquility, peace and rest.
NASA Astrophysics Data System (ADS)
Uchikawa, Joji; Zeebe, Richard
2010-05-01
Stable oxygen isotope (δ18O) values of foraminiferal calcites, which represent one of the most fundamental paleoceanographic tools to reconstruct ancient seawater temperatures, are influenced by seawater pH variations. Understanding the driving mechanism for such phenomenon requires precise knowledge of the equilibrium 18O fractionation factors between dissolved inorganic carbon (DIC) species and water. An experimental study by Beck et al. (2005) successfully refined the 18O fractionation factors between DIC components and water. Based on these results, the overall 18O fractionation between total DIC and water as a function of pH can be readily calculated (e.g., Zeebe, 2007). However, these calculations may not be applicable to seawater because the fractionation factors were measured in freshwater. Natural seawater contains numerous ionic species and other dissolved constituents, which may affect the fractionation factors. For example, it has been experimentally demonstrated that the presence of magnesium ions (Mg2+) in solutions affect equilibrium carbon isotope (13C) fractionation between aqueous CO2 and carbonate ions presumably due to the enrichment of 13C isotopes in Mg-CO30 complexes (Thode et al., 1965). This suggests that the presence of Mg2+ in solutions similarly affects the 18O fractionation factors between DIC species and water. On the other hand, Beck et al. (2005) concluded that the effect of ion pairs on the δ18O equilibrium appears to be negligible. However, this conclusion may not apply to ion paring in general, because experiments were not conducted for metal ions other than Na+. Given that Mg2+ has a marked effect on the equilibrium δ13C fractionation factors and Mg-CO30 is the most abundant form of metal-CO3-complexes in natural seawater, the potential effect of Mg2+ on the 18O fractionation factors between DIC components and water needs to be examined. Here, we will present preliminary results from quantitative carbonate precipitation
Frey, M.; Hunziker, J.C.; O'Neil, J.R.; Schwander, H.W.
1976-01-01
Nine samples from the Monte Rosa Granite have been investigated by microscopic, X-ray, wet chemical, electron microprobe, stable isotope and Rb-Sr and K-Ar methods. Two mineral assemblages have been distinguished by optical methods and dated as Permian and mid-Tertiary by means of Rb-Sr age determinations. The Permian assemblage comprises quartz, orthoclase, oligoclase, biotite, and muscovite whereas the Alpine assemblage comprises quartz, microcline, albite+epidote or oligoclase, biotite, and phengite. Disequilibrium between the Permian and Alpine mineral assemblages is documented by the following facts: (i) Two texturally distinguishable generations of white K-mica are 2 M muscovite (Si=3.1-3.2) and 2 M or 3 T phengite (Si=3.3-3.4). Five muscovites show Permian Rb-Sr ages and oxygen isotope fractionations indicating temperatures between 520 and 560 ?? C; however, K-Ar ages are mixed or rejuvenated. Phengite always shows mid-Tertiary Rb-Sr ages, (ii) Two biotite generations can be recognized, although textural evidence is often ambiguous. Three out of four texturally old biotites show mid-Tertiary Rb-Sr cooling ages while the oxygen isotopic fractionations point to Permian, mixed or Alpine temperatures, (iii) Comparison of radiogenic and stable isotope relations indicates that the radiogenic isotopes in the interlayer positions of the micas were mobilized during Alpine time without recrystallization, that is, without breaking Al-O or Si-O bonds. High Ti contents in young muscovites and biotites also indicate that the octahedral (and tetrahedral) sites remained undisturbed during rejuvenation. (iv) 'Isotopic reversals' in the order of O18 enrichment between K-feldspar and albite exist. Arguments for equilibrium during Permian time are meagre because of Alpine overprinting effects. Texturally old muscovites show high temperatures and Permian Rb-Sr ages in concordancy with Rb-Sr whole rock ages. For the tectonically least affected samples, excellent concordance
ERIC Educational Resources Information Center
Baehr, Marie
1994-01-01
Provides a problem where students are asked to find the point at which a soda can floating in some liquid changes its equilibrium between stable and unstable as the soda is removed from the can. Requires use of Newton's first law, center of mass, Archimedes' principle, stable and unstable equilibrium, and buoyant force position. (MVL)
DeLay, Dawn; Laursen, Brett; Kiuru, Noona; Poikkeus, Anna-Maija; Aunola, Kaisa; Nurmi, Jari-Erik
2015-01-01
This study is designed to investigate friend influence over mathematical reasoning in a sample of 374 children in 187 same-sex friend dyads (184 girls in 92 friendships; 190 boys in 95 friendships). Participants completed surveys that measured mathematical reasoning in the 3rd grade (approximately 9 years old) and one year later in the 4th grade (approximately 10 years old). Analyses designed for dyadic data (i.e., longitudinal Actor-Partner Interdependence Models) indicated that higher achieving friends influenced the mathematical reasoning of lower achieving friends, but not the reverse. Specifically, greater initial levels of mathematical reasoning among higher achieving partners in the 3rd grade predicted greater increases in mathematical reasoning from 3rd grade to 4th grade among lower achieving partners. These effects held after controlling for peer acceptance and rejection, task avoidance, interest in mathematics, maternal support for homework, parental education, length of the friendship, and friendship group norms on mathematical reasoning. PMID:26402901
Espino, Susana; Schenk, H. Jochen
2011-01-01
The maximum specific hydraulic conductivity (kmax) of a plant sample is a measure of the ability of a plants’ vascular system to transport water and dissolved nutrients under optimum conditions. Precise measurements of kmax are needed in comparative studies of hydraulic conductivity, as well as for measuring the formation and repair of xylem embolisms. Unstable measurements of kmax are a common problem when measuring woody plant samples and it is commonly observed that kmax declines from initially high values, especially when positive water pressure is used to flush out embolisms. This study was designed to test five hypotheses that could potentially explain declines in kmax under positive pressure: (i) non-steady-state flow; (ii) swelling of pectin hydrogels in inter-vessel pit membranes; (iii) nucleation and coalescence of bubbles at constrictions in the xylem; (iv) physiological wounding responses; and (v) passive wounding responses, such as clogging of the xylem by debris. Prehydrated woody stems from Laurus nobilis (Lauraceae) and Encelia farinosa (Asteraceae) collected from plants grown in the Fullerton Arboretum in Southern California, were used to test these hypotheses using a xylem embolism meter (XYL'EM). Treatments included simultaneous measurements of stem inflow and outflow, enzyme inhibitors, stem-debarking, low water temperatures, different water degassing techniques, and varied concentrations of calcium, potassium, magnesium, and copper salts in aqueous measurement solutions. Stable measurements of kmax were observed at concentrations of calcium, potassium, and magnesium salts high enough to suppress bubble coalescence, as well as with deionized water that was degassed using a membrane contactor under strong vacuum. Bubble formation and coalescence under positive pressure in the xylem therefore appear to be the main cause for declining kmax values. Our findings suggest that degassing of water is essential for achieving stable and precise
DeLay, Dawn; Laursen, Brett; Kiuru, Noona; Poikkeus, Anna-Maija; Aunola, Kaisa; Nurmi, Jari-Erik
2015-11-01
This study was designed to investigate friend influence over mathematical reasoning in a sample of 374 children in 187 same-sex friend dyads (184 girls in 92 friendships; 190 boys in 95 friendships). Participants completed surveys that measured mathematical reasoning in the 3rd grade (approximately 9 years old) and 1 year later in the 4th grade (approximately 10 years old). Analyses designed for dyadic data (i.e., longitudinal actor-partner interdependence model) indicated that higher achieving friends influenced the mathematical reasoning of lower achieving friends, but not the reverse. Specifically, greater initial levels of mathematical reasoning among higher achieving partners in the 3rd grade predicted greater increases in mathematical reasoning from 3rd grade to 4th grade among lower achieving partners. These effects held after controlling for peer acceptance and rejection, task avoidance, interest in mathematics, maternal support for homework, parental education, length of the friendship, and friendship group norms on mathematical reasoning.
ERIC Educational Resources Information Center
Whitesell, Emilyn Ruble; Stiefel, Leanna; Schwartz, Amy Ellen
2016-01-01
Across the country and in urban areas in particular, many students change schools during the academic year. While much research documents the impact of changing schools on the academic achievement of mobile students themselves, less research explores whether new arrivals have negative spillovers on stable classmates. The lack of research on…
NASA Astrophysics Data System (ADS)
Mienis, F.
Living corals, molluscs and associated water samples were collected from deep sea coral reefs along the margins of Rockall Trough (N. Atlantic). Oxygen (d18O) and carbon (d13C) isotope analyses of seawater and skeletal CaCO3 indicate that vari- ous organisms do not precipitate CaCO3 in isotopic equilibrium with host water. Par- ticularly the most abundant coral genera Lophelia sp and Madrepora sp fractionate markedly, as was already observed by a number of previous studies. However, our new data shows that the coral genus Stylaster, occuring in small numbers in the Rock- all Trough area, is in isotopic equilibrium with seawater. Like for the aragonitic bi- valves and gastropods inhabiting the same deep water reefs, microsampling of growth banded Stylaster specimens can be applied to obtain high resolution time series of in-equilibrium d13C and d18O data covering the life span of individual specimens.
Padowski, Jeannie M; Pollack, Gary M
2011-12-02
Active efflux transport processes at the blood-brain barrier (BBB), such as P-glycoprotein (P-gp)-mediated efflux, can limit brain uptake of therapeutics. Accurate determination of the consequent impact on brain uptake is assumed to require sampling post-attainment of brain-to-blood distribution equilibrium. Because this approach is not always feasible, understanding the relationship between apparent degree of efflux (e.g., calculated BBB P-gp effect) and the fraction of time remaining until distribution equilibrium is achieved (FTDE) would be advantageous. This study employed simulation strategies to explore this relationship in the simplest relevant system (absence of protein binding, saturable uptake, or metabolism at the BBB). Concentration-time profiles were simulated with a 4-compartment system (blood, peripheral tissues, BBB endothelium and brain parenchyma). A unidirectional endothelium-to-blood rate constant, PS(e), represented P-gp-mediated efflux. A parameter space was selected to simulate an 18-fold P-gp effect, (K(p,brain) at distribution equilibrium in the absence [K(p,brain)=82] vs. presence [K(p,brain)=4.5] of P-gp-mediated flux), as observed for paclitaxel in P-gp-deficient vs. P-gp-competent mice. Hypothetical compounds with different P-gp effects, peripheral compartment distribution kinetics, or times to achieve distribution equilibrium were simulated by perturbing the values of relevant model parameters. P-gp effects calculated prior to attainment of distribution equilibrium may be substantially erroneous. However, reasonably accurate estimates can be obtained relatively early in the net distributional phase (under 20% error at FTDE>0.36 or 0.11 for bolus or infusion administration, respectively). Potential errors associated with non-equilibrium calculations are dependent on both P-gp-mediated and P-gp-independent components of flux across the BBB.
Achieving a stable time response in polymeric radiation sensors under charge injection by X-rays.
Intaniwet, Akarin; Mills, Christopher A; Sellin, Paul J; Shkunov, Maxim; Keddie, Joseph L
2010-06-01
Existing inorganic materials for radiation sensors suffer from several drawbacks, including their inability to cover large curved areas, lack of tissue-equivalence, toxicity, and mechanical inflexibility. As an alternative to inorganics, poly(triarylamine) (PTAA) diodes have been evaluated for their suitability for detecting radiation via the direct creation of X-ray induced photocurrents. A single layer of PTAA is deposited on indium tin oxide (ITO) substrates, with top electrodes selected from Al, Au, Ni, and Pd. The choice of metal electrode has a pronounced effect on the performance of the device; there is a direct correlation between the diode rectification factor and the metal-PTAA barrier height. A diode with an Al contact shows the highest quality of rectifying junction, and it produces a high X-ray photocurrent (several nA) that is stable during continuous exposure to 50 kV Mo Kalpha X-radiation over long time scales, combined with a high signal-to-noise ratio with fast response times of less than 0.25 s. Diodes with a low band gap, 'Ohmic' contact, such as ITO/PTAA/Au, show a slow transient response. This result can be explained by the build-up of space charge at the metal-PTAA interface, caused by a high level of charge injection due to X-ray-induced carriers. These data provide new insights into the optimum selection of metals for Schottky contacts on organic materials, with wider applications in light sensors and photovoltaic devices.
Cruz, C.; Soares-Pinto, D. O.; Brandão, P.; dos Santos, A. M.; Reis, M. S.
2016-03-07
The control of quantum correlations in solid-state systems by means of material engineering is a broad avenue to be explored, since it makes possible steps toward the limits of quantum mechanics and the design of novel materials with applications on emerging quantum technologies. This letter explores the potential of molecular magnets to be prototypes of materials for quantum information technology in this context. More precisely, we engineered a material and from its geometric quantum discord we found significant quantum correlations up to 9540 K (even without entanglement); and, a pure singlet state occupied up to around 80 K (above liquid nitrogen temperature), additionally. Our results could only be achieved due to the carboxylate group promoting a metal-to-metal huge magnetic interaction.
Cruz, C.; Soares-Pinto, D. O.; Brandão, P.; ...
2016-03-07
The control of quantum correlations in solid-state systems by means of material engineering is a broad avenue to be explored, since it makes possible steps toward the limits of quantum mechanics and the design of novel materials with applications on emerging quantum technologies. This letter explores the potential of molecular magnets to be prototypes of materials for quantum information technology in this context. More precisely, we engineered a material and from its geometric quantum discord we found significant quantum correlations up to 9540 K (even without entanglement); and, a pure singlet state occupied up to around 80 K (above liquidmore » nitrogen temperature), additionally. Our results could only be achieved due to the carboxylate group promoting a metal-to-metal huge magnetic interaction.« less
NASA Astrophysics Data System (ADS)
Cruz, C.; Soares-Pinto, D. O.; Brandão, P.; dos Santos, A. M.; Reis, M. S.
2016-02-01
The control of quantum correlations in solid-state systems by means of material engineering is a broad avenue to be explored, since it makes possible steps toward the limits of quantum mechanics and the design of novel materials with applications on emerging quantum technologies. In this context, this letter explores the potential of molecular magnets to be prototypes of materials for quantum information technology. More precisely, we engineered a material and from its geometric quantum discord we found significant quantum correlations up to 9540 K (even without entanglement); and, in addition, a pure singlet state occupied up to around 80 K (above liquid nitrogen temperature). These results could only be achieved due to the carboxylate group promoting a metal-to-metal huge magnetic interaction.
Haeufle, D F B; Grimmer, S; Seyfarth, A
2010-03-01
A reductionist approach was presented to investigate which level of detail of the physiological muscle is required for stable locomotion. Periodic movements of a simplified one-dimensional hopping model with a Hill-type muscle (one contractile element, neither serial nor parallel elastic elements) were analyzed. Force-length and force-velocity relations of the muscle were varied in three levels of approximation (constant, linear and Hill-shaped nonlinear) resulting in nine different hopping models of different complexity. Stability of these models was evaluated by return map analysis and the performance by the maximum hopping height. The simplest model (constant force-length and constant force-velocity relations) outperformed all others in the maximum hopping height but was unstable. Stable hopping was achieved with linear and Hill-shaped nonlinear characteristic of the force-velocity relation. The characteristics of the force-length relation marginally influenced hopping stability. The results of this approach indicate that the intrinsic properties of the contractile element are responsible for stabilization of periodic movements. This connotes that (a) complex movements like legged locomotion could benefit from stabilizing effects of muscle properties, and (b) technical systems could benefit from the emerging stability when implementing biological characteristics into artificial muscles.
Wang, Dongbo; Wang, Qilin; Laloo, Andrew; Xu, Yifeng; Bond, Philip L.; Yuan, Zhiguo
2016-01-01
Stable nitritation is a critical bottleneck for achieving autotrophic nitrogen removal using the energy-saving mainstream deammonification process. Herein we report a new strategy to wash out both the Nitrospira sp. and Nitrobacter sp. from the treatment of domestic-strength wastewater. The strategy combines sludge treatment using free nitrous acid (FNA) with dissolved oxygen (DO) control in the nitritation reactor. Initially, the nitrifying reactor achieved full conversion of NH4+ to NO3−. Then, nitrite accumulation at ~60% was achieved in the reactor when 1/4 of the sludge was treated daily with FNA at 1.82 mg N/L in a side-stream unit for 24 h. Fluorescence in-situ hybridization (FISH) revealed FNA treatment substantially reduced the abundance of nitrite oxidizing bacteria (NOB) (from 23.0 ± 4.3 to 5.3 ± 1.9%), especially that of Nitrospira sp. (from 15.7 ± 3.9 to 0.4 ± 0.1%). Nitrite accumulation increased to ~80% when the DO concentration in the mainstream reactor was reduced from 2.5–3.0 to 0.3–0.8 mg/L. FISH revealed the DO limitation further reduced the abundance of NOB (to 2.1 ± 1.0%), especially that of Nitrobacter sp. (from 4.9 ± 1.2 to 1.8 ± 0.8%). The strategy developed removes a major barrier for deammonification in low-strength domestic wastewater. PMID:27151247
NASA Astrophysics Data System (ADS)
Wang, Dongbo; Wang, Qilin; Laloo, Andrew; Xu, Yifeng; Bond, Philip L.; Yuan, Zhiguo
2016-05-01
Stable nitritation is a critical bottleneck for achieving autotrophic nitrogen removal using the energy-saving mainstream deammonification process. Herein we report a new strategy to wash out both the Nitrospira sp. and Nitrobacter sp. from the treatment of domestic-strength wastewater. The strategy combines sludge treatment using free nitrous acid (FNA) with dissolved oxygen (DO) control in the nitritation reactor. Initially, the nitrifying reactor achieved full conversion of NH4+ to NO3-. Then, nitrite accumulation at ~60% was achieved in the reactor when 1/4 of the sludge was treated daily with FNA at 1.82 mg N/L in a side-stream unit for 24 h. Fluorescence in-situ hybridization (FISH) revealed FNA treatment substantially reduced the abundance of nitrite oxidizing bacteria (NOB) (from 23.0 ± 4.3 to 5.3 ± 1.9%), especially that of Nitrospira sp. (from 15.7 ± 3.9 to 0.4 ± 0.1%). Nitrite accumulation increased to ~80% when the DO concentration in the mainstream reactor was reduced from 2.5-3.0 to 0.3-0.8 mg/L. FISH revealed the DO limitation further reduced the abundance of NOB (to 2.1 ± 1.0%), especially that of Nitrobacter sp. (from 4.9 ± 1.2 to 1.8 ± 0.8%). The strategy developed removes a major barrier for deammonification in low-strength domestic wastewater.
Dynamically stable magnetic suspension/bearing system
Post, R.F.
1996-02-27
A magnetic bearing system contains magnetic subsystems which act together to support a rotating element in a state of dynamic equilibrium. However, owing to the limitations imposed by Earnshaw`s Theorem, the magnetic bearing systems to be described do not possess a stable equilibrium at zero rotational speed. Therefore, mechanical stabilizers are provided, in each case, to hold the suspended system in equilibrium until its speed has exceeded a low critical speed where dynamic effects take over, permitting the achievement of a stable equilibrium for the rotating object. A state of stable equilibrium is achieved above a critical speed by use of a collection of passive elements using permanent magnets to provide their magnetomotive excitation. The magnetic forces exerted by these elements, when taken together, levitate the rotating object in equilibrium against external forces, such as the force of gravity or forces arising from accelerations. At the same time, this equilibrium is made stable against displacements of the rotating object from its equilibrium position by using combinations of elements that possess force derivatives of such magnitudes and signs that they can satisfy the conditions required for a rotating body to be stably supported by a magnetic bearing system over a finite range of those displacements. 32 figs.
Dynamically stable magnetic suspension/bearing system
Post, Richard F.
1996-01-01
A magnetic bearing system contains magnetic subsystems which act together to support a rotating element in a state of dynamic equilibrium. However, owing to the limitations imposed by Earnshaw's Theorem, the magnetic bearing systems to be described do not possess a stable equilibrium at zero rotational speed. Therefore, mechanical stabilizers are provided, in each case, to hold the suspended system in equilibrium until its speed has exceeded a low critical speed where dynamic effects take over, permitting the achievement of a stable equilibrium for the rotating object. A state of stable equilibrium is achieved above a critical speed by use of a collection of passive elements using permanent magnets to provide their magnetomotive excitation. The magnetic forces exerted by these elements, when taken together, levitate the rotating object in equilibrium against external forces, such as the force of gravity or forces arising from accelerations. At the same time, this equilibrium is made stable against displacements of the rotating object from its equilibrium position by using combinations of elements that possess force derivatives of such magnitudes and signs that they can satisfy the conditions required for a rotating body to be stably supported by a magnetic bearing system over a finite range of those displacements.
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
ERIC Educational Resources Information Center
Marks, Gary N.
2016-01-01
Multi-domain and longitudinal studies of student achievement routinely find moderate to strong correlations across achievement domains and even stronger within-domain correlations over time. The purpose of this study is to examine the sources of these patterns analysing student achievement in 5 domains across Years 3, 5 and 7. The analysis is of…
ERIC Educational Resources Information Center
Schulte, Ann C.; Stevens, Joseph J.; Elliott, Stephen N.; Tindal, Gerald; Nese, Joseph F. T.
2016-01-01
Reading comprehension growth trajectories from 3rd to 7th grade were estimated for 99,919 students on a state reading comprehension assessment. We examined whether differences between students in general education (GE) and groups of students identified as exceptional learners were best characterized as stable, widening, or narrowing. The groups…
Highly air- and moisture-stable hole-doped carbon nanotube films achieved using boron-based oxidant
NASA Astrophysics Data System (ADS)
Funahashi, Kazuma; Tanaka, Naoki; Shoji, Yoshiaki; Imazu, Naoki; Nakayama, Ko; Kanahashi, Kaito; Shirae, Hiroyuki; Noda, Suguru; Ohta, Hiromichi; Fukushima, Takanori; Takenobu, Taishi
2017-03-01
Hole doping into carbon nanotubes can be achieved. However, the doped nanotubes usually suffer from the lack of air and moisture stability, thus, they eventually lose their improved electrical properties. Here, we report that a salt of the two-coordinate boron cation Mes2B+ (Mes: 2,4,6-trimethylphenyl group) can serve as an efficient hole-doping reagent to produce nanotubes with markedly high stability in the presence of air and moisture. Upon doping, the resistances of the nanotubes decreased, and these states were maintained for one month in air. The hole-doped nanotube films showed a minimal increase in resistance even upon humidification with a relative humidity of 90%.
ERIC Educational Resources Information Center
Marsh, Herbert W.; Pekrun, Reinhard; Lichtenfeld, Stephanie; Guo, Jiesi; Arens, A. Katrin; Murayama, Kou
2016-01-01
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…
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.
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.
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)
Shen, X. F.; Qiao, B.; Chang, H. X.; Kar, S.; Zhou, C. T.; Borghesi, M.; He, X. T.
2016-10-01
Generation of monoenergetic heavy ion beams aroused more scientific interest in recent years. Radiation pressure acceleration (RPA) is an ideal mechanism for obtaining high-quality heavy ion beams, in principle. However, to achieve the same energy per nucleon (velocity) as protons, heavy ions undergo much more serious Rayleigh-Taylor-like (RT) instability and afterwards much worse Coulomb explosion due to loss of co-moving electrons. This leads to premature acceleration termination of heavy ions and very low energy attained in experiment. The utilization of a high-Z coating in front of the target may suppress the RT instability and Coulomb explosion by continuously replenishing the accelerating heavy ion foil with co-moving electrons due to its successive ionization under laser fields with Gaussian temporal and spatial profiles. Thus stable RPA can be realized. Two-dimensional and three-dimensional particles-in-cell simulations with dynamic ionization show that a monoenergetic Al13+ beam with peak energy 4.0GeV and particle number 1010 (charge > 20nC) can be obtained at intensity 1022 W/cm2. Supported by the NSF, Nos. 11575298 and 1000-Talents Program of China.
Equilibrium field coil concepts for INTOR
Strickler, D.J.; Peng, Y.K.M.; Brown, T.G.
1981-08-01
Methods are presented for reducing ampere-turn requirements in the EF coil system. It is shown that coil currents in an EF coil system external to the toroidal field coils can be substantially reduced by relaxing the triangularity of a D-shaped plasma. Further reductions are realized through a hybrid EF coil system using both internal and external coils. Equilibrium field coils for a poloidally asymmetric, single-null INTOR configuration are presented. It is shown that the shape of field lines in the plasma scrapeoff region and divertor channel improves as triangularity is reduced, but it does so at the possible expense of achievable stable beta values.
1982-09-01
that for variouis standard types of equilibria* they hold. In particular, if one uses the teaporary equilibrium framework one can use the standard ...T, the integral converges toward f’ia(da) f fU(b~dc)6(a,b,c)T( asdm ) A B C which is fR (da) f d(lib,c) U0 T (cab) A BxC Me converse Is obvious
Equilibrium Shape of Colloidal Crystals.
Sehgal, Ray M; Maroudas, Dimitrios
2015-10-27
Assembling colloidal particles into highly ordered configurations, such as photonic crystals, has significant potential for enabling a broad range of new technologies. Facilitating the nucleation of colloidal crystals and developing successful crystal growth strategies require a fundamental understanding of the equilibrium structure and morphology of small colloidal assemblies. Here, we report the results of a novel computational approach to determine the equilibrium shape of assemblies of colloidal particles that interact via an experimentally validated pair potential. While the well-known Wulff construction can accurately capture the equilibrium shape of large colloidal assemblies, containing O(10(4)) or more particles, determining the equilibrium shape of small colloidal assemblies of O(10) particles requires a generalized Wulff construction technique which we have developed for a proper description of equilibrium structure and morphology of small crystals. We identify and characterize fully several "magic" clusters which are significantly more stable than other similarly sized clusters.
Local Nash equilibrium in social networks.
Zhang, Yichao; Aziz-Alaoui, M A; Bertelle, Cyrille; Guan, Jihong
2014-08-29
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.
Zhang, Xueyu; Zheng, Shaokui; Xiao, Xuze; Wang, Lu; Yin, Yunjun
2017-02-01
This study investigated the long-term treatment performance of a conventional activated sludge (AS) process operating at a microaerobic DO level (0.5-1.0mg·L(-1)) in the aeration tank and a long settling time of >10h in the clarification tank for sewage treatment. The microaerobic DO conditions led to severe sludge bulking. However, good sludge/water separation and excellent pollutant removal performance (COD, 95±2%; NH4(+)-N, 99±1%; and TN, 69±6%) were stably achieved in the microaerobic AS system during its 150days of continuous operation. This is the first report to demonstrate that a long settling time effectively overcame the effect of severe filamentous bulking in conventional AS process, and that microaerobic DO conditions achieved excellent simultaneous nitrification and denitrification reactions in the aeration tank. The process characteristics of the microaerobic AS system differed substantially from those existing biological denitrification processes, including A/O, CANON, and OLAND processes.
Ogita, Manabu; Miyauchi, Katsumi; Miyazaki, Tadashi; Naito, Ryo; Konishi, Hirokazu; Tsuboi, Shuta; Dohi, Tomotaka; Kasai, Takatoshi; Yokoyama, Takayuki; Okazaki, Shinya; Kurata, Takeshi; Daida, Hiroyuki
2014-01-01
Diabetes mellitus is recognized an independent risk factor for coronary artery disease (CAD) and mortality. Clinical trials have shown that statins significantly reduce cardiovascular events in diabetic patients. However, residual cardiovascular risk persists despite the achievement of target low-density lipoprotein cholesterol (LDL-C) levels with statin. High-density lipoprotein cholesterol (HDL-C) is an established coronary risk factor that is independent of LDL-C levels. We evaluated the impact of HDL-C on long-term mortality in diabetic patients with stable CAD who achieved optimal LDL-C. We enrolled 438 consecutive diabetic patients who were scheduled for percutaneous coronary intervention between 2004 and 2007 at our institution. We identified 165 patients who achieved target LDL-C <100 mg/dl. Patients were stratified into two groups according to HDL-C levels (low HDL-C group, baseline HDL-C <40 mg/dl; high HDL-C group, ≥40 mg/dl). Major adverse cardiac events (MACE) that included all-cause death, acute coronary syndrome, and target lesion revascularization were evaluated between the two groups. The median follow-up period was 946 days. The rate of MACE was significantly higher in diabetic patients with low-HDL-C who achieved optimal LDL-C (6.9 vs 17.9 %, log-rank P = 0.030). Multivariate Cox regression analysis showed that HDL-C is significantly associated with clinical outcomes (adjusted hazard ratio for MACE 1.33, 95 % confidence interval 1.01-1.75, P = 0.042). Low HDL-C is a residual risk factor that is significantly associated with long-term clinical outcomes among diabetic patients with stable CAD who achieve optimal LDL-C levels.
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
The Equilibrium Between Titanium Ions and Titanium Metal in NaCl-KCl Equimolar Molten Salt
NASA Astrophysics Data System (ADS)
Wang, Qiuyu; Song, Jianxun; Hu, Guojing; Zhu, Xiaobo; Hou, Jungang; Jiao, Shuqiang; Zhu, Hongmin
2013-08-01
The equilibrium between metallic titanium and titanium ions, 3Ti2+ ⇌ 2Ti3+ + Ti, in NaCl-KCl equimolar molten salt was reevaluated. At a fixed temperature and an initial concentration of titanium chloride, the equilibrium was achieved by adding an excess amount of sponge titanium in assistant with bubbling of argon into the molten salt. The significance of this work is that the accurate concentrations of titanium ions have been obtained based on a reliable approach for taking samples. Furthermore, the equilibrium constant {{K}}_{{C}} = (x_{{{{Ti}}^{{ 3 { + }}} }}^{{eql}} )3 /(x_{{{{Ti}}^{{ 2 { + }}} }}^{{eql}} )2 was calculated through the best-fitting method under the consideration of the TiOCl dissolution. Indeed, the final results have disclosed that the stable value of KC could be achieved based on all modifications.
Stable Spheromaks with Profile Control
Fowler, T K; Jayakumar, R
2008-01-29
A spheromak equilibrium with zero edge current is shown to be stable to both ideal MHD and tearing modes that normally produce Taylor relaxation in gun-injected spheromaks. This stable equilibrium differs from the stable Taylor state in that the current density j falls to zero at the wall. Estimates indicate that this current profile could be sustained by non-inductive current drive at acceptable power levels. Stability is determined using the NIMROD code for linear stability analysis. Non-linear NIMROD calculations with non-inductive current drive could point the way to improved fusion reactors.
Accelerating Multiagent Reinforcement Learning by Equilibrium Transfer.
Hu, Yujing; Gao, Yang; An, Bo
2015-07-01
An important approach in multiagent reinforcement learning (MARL) is equilibrium-based MARL, which adopts equilibrium solution concepts in game theory and requires agents to play equilibrium strategies at each state. However, most existing equilibrium-based MARL algorithms cannot scale due to a large number of computationally expensive equilibrium computations (e.g., computing Nash equilibria is PPAD-hard) during learning. For the first time, this paper finds that during the learning process of equilibrium-based MARL, the one-shot games corresponding to each state's successive visits often have the same or similar equilibria (for some states more than 90% of games corresponding to successive visits have similar equilibria). Inspired by this observation, this paper proposes to use equilibrium transfer to accelerate equilibrium-based MARL. The key idea of equilibrium transfer is to reuse previously computed equilibria when each agent has a small incentive to deviate. By introducing transfer loss and transfer condition, a novel framework called equilibrium transfer-based MARL is proposed. We prove that although equilibrium transfer brings transfer loss, equilibrium-based MARL algorithms can still converge to an equilibrium policy under certain assumptions. Experimental results in widely used benchmarks (e.g., grid world game, soccer game, and wall game) show that the proposed framework: 1) not only significantly accelerates equilibrium-based MARL (up to 96.7% reduction in learning time), but also achieves higher average rewards than algorithms without equilibrium transfer and 2) scales significantly better than algorithms without equilibrium transfer when the state/action space grows and the number of agents increases.
Tsventoukh, M. M.
2010-10-15
A study is made of the convective (interchange, or flute) plasma stability consistent with equilibrium in magnetic confinement systems with a magnetic field decreasing outward and large curvature of magnetic field lines. Algorithms are developed which calculate convective plasma stability from the Kruskal-Oberman kinetic criterion and in which the convective stability is iteratively consistent with MHD equilibrium for a given pressure and a given type of anisotropy in actual magnetic geometry. Vacuum and equilibrium convectively stable configurations in systems with a decreasing, highly curved magnetic field are calculated. It is shown that, in convectively stable equilibrium, the possibility of achieving high plasma pressures in the central region is restricted either by the expansion of the separatrix (when there are large regions of a weak magnetic field) or by the filamentation of the gradient plasma current (when there are small regions of a weak magnetic field, in which case the pressure drops mainly near the separatrix). It is found that, from the standpoint of equilibrium and of the onset of nonpotential ballooning modes, a kinetic description of convective stability yields better plasma confinement parameters in systems with a decreasing, highly curved magnetic field than a simpler MHD model and makes it possible to substantially improve the confinement parameters for a given type of anisotropy. For the Magnetor experimental compact device, the maximum central pressure consistent with equilibrium and stability is calculated to be as high as {beta} {approx} 30%. It is shown that, for the anisotropy of the distribution function that is typical of a background ECR plasma, the limiting pressure gradient is about two times steeper than that for an isotropic plasma. From a practical point of view, the possibility is demonstrated of achieving better confinement parameters of a hot collisionless plasma in systems with a decreasing, highly curved magnetic field
Radiative-dynamical equilibrium states for Jupiter
NASA Technical Reports Server (NTRS)
Trafton, L. M.; Stone, P. H.
1974-01-01
In order to obtain accurate estimates of the radiative heating that drives motions in Jupiter's atmosphere, previous radiative equilibrium calculations are improved by including the NH3 opacities and updated results for the pressure-induced opacities. These additions increase the radiative lapse rate near the top of the statically unstable region and lead to a fairly constant radiative lapse rate below the tropopause. The radiative-convective equilibrium temperature structure consistent with these changes is calculated, but it differs only slightly from earlier calculations. The radiative equilibrium calculations are used to calculate whether equilibrium states can occur on Jupiter which are similar to the baroclinic instability regimes on the earth and Mars. The results show that Jupiter's dynamical regime cannot be of this kind, except possibly at very high latitudes, and that its regime must be a basically less stable one than this kind.
Constructing a Chaotic System with an Infinite Number of Equilibrium Points
NASA Astrophysics Data System (ADS)
Pham, Viet-Thanh; Jafari, Sajad; Kapitaniak, Tomasz
2016-12-01
The chaotic systems with hidden attractors, such as chaotic systems with a stable equilibrium, chaotic systems with infinite equilibria or chaotic systems with no equilibrium have been investigated recently. However, the relationships between them still need to be discovered. This work explains how to transform a system with one stable equilibrium into a new system with an infinite number of equilibrium points by using a memristive device. Furthermore, some other new systems with infinite equilibria are also constructed to illustrate the introduced methodology.
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…
Conditions for equilibrium solid-stabilized emulsions.
Kraft, Daniela J; de Folter, Julius W J; Luigjes, Bob; Castillo, Sonja I R; Sacanna, Stefano; Philipse, Albert P; Kegel, Willem K
2010-08-19
Particular types of solid-stabilized emulsions can be thermodynamically stable as evidenced by their spontaneous formation and monodisperse droplet size, which only depends on system parameters. Here, we investigate the generality of these equilibrium solid-stabilized emulsions with respect to the basic constituents: aqueous phase with ions, oil, and stabilizing particles. From systematic variations of these constituents, we identify general conditions for the spontaneous formation of monodisperse solid-stabilized emulsions droplets. We conclude that emulsion stability is achieved by a combination of solid particles as well as amphiphilic ions adsorbed at the droplet surface, and low interfacial tensions of the bare oil-water interface of order 10 mN/m or below. Furthermore, preferential wetting of the colloidal particles by the oil phase is necessary for thermodynamic stability. We demonstrate the sufficiency of these basic requirements by extending the observed thermodynamic stability to emulsions of different compositions. Our findings point to a new class of colloid-stabilized meso-emulsions with a potentially high impact on industrial emulsification processes due to the associated large energy savings.
NASA Astrophysics Data System (ADS)
You, K.-I.; Lee, D.-K.; Lee, S. G.; Bak, J. G.; Hahn, S. H.; Lao, L.; Kstar Team
2011-10-01
We have installed the EFIT code on our computing system and made some modification to reconstruct the plasma equilibrium of KSTAR (Korea Superconducting Tokamak Advanced Research). KSTAR PF and TF coil systems use a CICC (Cable-In-Conduit Conductor) type superconductor. The CICC jacket material for most PF and all TF coils is Incoloy 908, which is a magnetic material with relative magnetic permeability greater than 10 in low external field. We newly introduced Diamagnetic Loop and variational Motion Stark Effect signals to equilibrium reconstruction. In this paper, we present some results of equilibrium reconstruction with the EFIT code, assess the effects of newly introduced diagnsotics signal on the equilibrium reconstruction and compare the EFIT results with the various diagnostics data in various plasma conditions including H- and L- modes. In addition, we will show the Incoloy908 effects on the plasma equilibrium.
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.
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)
Response reactions: equilibrium coupling.
Hoffmann, Eufrozina A; Nagypal, Istvan
2006-06-01
It is pointed out and illustrated in the present paper that if a homogeneous multiple equilibrium system containing k components and q species is composed of the reactants actually taken and their reactions contain only k + 1 species, then we have a unique representation with (q - k) stoichiometrically independent reactions (SIRs). We define these as coupling reactions. All the other possible combinations with k + 1 species are the coupled reactions that are in equilibrium when the (q - k) SIRs are in equilibrium. The response of the equilibrium state for perturbation is determined by the coupling and coupled equilibria. Depending on the circumstances and the actual thermodynamic data, the effect of coupled equilibria may overtake the effect of the coupling ones, leading to phenomena that are in apparent contradiction with Le Chatelier's principle.
Inferring unstable equilibrium configurations from experimental data
NASA Astrophysics Data System (ADS)
Virgin, L. N.; Wiebe, R.; Spottswood, S. M.; Beberniss, T.
2016-09-01
This research considers the structural behavior of slender, mechanically buckled beams and panels of the type commonly found in aerospace structures. The specimens were deflected and then clamped in a rigid frame in order to exhibit snap-through. That is, the initial equilibrium and the buckled (snapped-through) equilibrium configurations both co-existed for the given clamped conditions. In order to transit between these two stable equilibrium configurations (for example, under the action of an externally applied load), it is necessary for the structural component to pass through an intermediate unstable equilibrium configuration. A sequence of sudden impacts was imparted to the system, of various strengths and at various locations. The goal of this impact force was to induce relatively intermediate-sized transients that effectively slowed-down in the vicinity of the unstable equilibrium configuration. Thus, monitoring the velocity of the motion, and specifically its slowing down, should give an indication of the presence of an equilibrium configuration, even though it is unstable and not amenable to direct experimental observation. A digital image correlation (DIC) system was used in conjunction with an instrumented impact hammer to track trajectories and statistical methods used to infer the presence of unstable equilibria in both a beam and a panel.
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.
NASA Astrophysics Data System (ADS)
Semelsberger, Troy A.; Borup, Rodney L.
The production of a hydrogen-rich fuel-cell feed by dimethyl ether (DME) steam reforming was investigated using calculations of thermodynamic equilibrium as a function of steam-to-carbon ratio (0.00-4.00), temperature (100-600 °C), pressure (1-5 atm), and product species. Species considered were acetone, acetylene, carbon dioxide, carbon monoxide, dimethyl ether, ethane, ethanol, ethylene, formaldehyde, formic acid, hydrogen, isopropanol, methane, methanol, methyl-ethyl ether, n-propanol and water. Thermodynamic equilibrium calculations of DME steam reforming indicate complete conversion of dimethyl ether to hydrogen, carbon monoxide and carbon dioxide at temperatures greater than 200 °C and steam-to-carbon ratios greater than 1.25 at atmospheric pressure ( P = 1 atm). Increasing the operating pressure shifts the equilibrium toward the reactants; increasing the pressure from 1 to 5 atm decreases the conversion of dimethyl ether from 99.5 to 76.2%. The trend of thermodynamically stable products in decreasing mole fraction is methane, ethane, isopropyl alcohol, acetone, n-propanol, ethylene, ethanol, methyl-ethyl ether and methanol-formaldehyde, formic acid, and acetylene were not observed. Based on the equilibrium calculations, the optimal processing conditions for dimethyl ether steam reforming occur at a steam-to-carbon ratio of 1.50, a pressure of 1 atm, and a temperature of 200 °C. These thermodynamic equilibrium calculations show dimethyl ether processed with steam will produce hydrogen-rich fuel-cell feeds—with hydrogen concentrations exceeding 70%. The conversion of dimethyl ether via hydrolysis (considering methanol as the only product) is limited by thermodynamic equilibrium. Equilibrium conversion increases with temperature and steam-to-carbon ratio. A maximum dimethyl ether conversion of 62% is achieved at a steam-to-carbon ratio of 5.00 and a processing temperature of 600 °C.
Teaching Chemical Equilibrium with the Jigsaw Technique
NASA Astrophysics Data System (ADS)
Doymus, Kemal
2008-03-01
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 was randomly assigned as the non-jigsaw group (control) and other as the jigsaw group (cooperative). Students participating in the jigsaw group were divided into four “home groups” since the topic chemical equilibrium is divided into four subtopics (Modules A, B, C and D). Each of these home groups contained four students. The groups were as follows: (1) Home Group A (HGA), representin g the equilibrium state and quantitative aspects of equilibrium (Module A), (2) Home Group B (HGB), representing the equilibrium constant and relationships involving equilibrium constants (Module B), (3) Home Group C (HGC), representing Altering Equilibrium Conditions: Le Chatelier’s principle (Module C), and (4) Home Group D (HGD), representing calculations with equilibrium constants (Module D). The home groups then broke apart, like pieces of a jigsaw puzzle, and the students moved into jigsaw groups consisting of members from the other home groups who were assigned the same portion of the material. The jigsaw groups were then in charge of teaching their specific subtopic to the rest of the students in their learning group. The main data collection tool was a Chemical Equilibrium Achievement Test (CEAT), which was applied to both the jigsaw and non-jigsaw groups The results indicated that the jigsaw group was more successful than the non-jigsaw group (individual learning method).
Contact angle measurements under thermodynamic equilibrium conditions.
Lages, Carol; Méndez, Eduardo
2007-08-01
The precise control of the ambient humidity during contact angle measurements is needed to obtain stable and valid data. For a such purpose, a simple low-cost device was designed, and several modified surfaces relevant to biosensor design were studied. Static contact angle values for these surfaces are lower than advancing contact angles published for ambient conditions, indicating that thermodynamic equilibrium conditions are needed to avoid drop evaporation during the measurements.
Stable Stratification for Solar Ponds
NASA Technical Reports Server (NTRS)
Mehta, G. D.
1982-01-01
Stable density gradient forms in pond saturated with disodium phosphate (DSP). Volume of DSP saturated water tends to develop temperature and density layers. Since tests indicate thermal and density gradients remain in equilibrium at heat removal rates of 60 percent or more of heat input rate, pond containing DSP would be suitable for collecting solar energy and transferring it to heat exchanger for practical use.
Determination of nonaxisymmetric equilibrium
Elkin, D.
1980-01-01
The Princeton Equilibrium Code is modified to determine the equilibrium surfaces for a large aspect ratio toroidal system with helical magnetic fields. The code may easily be made to include any variety of modes. Verification of the code is made by comparison with an analytic solution for l = 3. Previously observed shifting of the magnetic axis with increasing pressure or with a changed externally applied vertical field is obtained. The case l = 0, a bumpy torus, gives convergence only for the lenient convergence tolerance of epsilon/sub b/ = 1.0 x 10-/sup 2/.
Beyond Equilibrium Thermodynamics
NASA Astrophysics Data System (ADS)
Öttinger, Hans Christian
2005-01-01
Beyond Equilibrium Thermodynamics fills a niche in the market by providing a comprehensive introduction to a new, emerging topic in the field. The importance of non-equilibrium thermodynamics is addressed in order to fully understand how a system works, whether it is in a biological system like the brain or a system that develops plastic. In order to fully grasp the subject, the book clearly explains the physical concepts and mathematics involved, as well as presenting problems and solutions; over 200 exercises and answers are included. Engineers, scientists, and applied mathematicians can all use the book to address their problems in modelling, calculating, and understanding dynamic responses of materials.
Adaptive behaviour and multiple equilibrium states in a predator-prey model.
Pimenov, Alexander; Kelly, Thomas C; Korobeinikov, Andrei; O'Callaghan, Michael J A; Rachinskii, Dmitrii
2015-05-01
There is evidence that multiple stable equilibrium states are possible in real-life ecological systems. Phenomenological mathematical models which exhibit such properties can be constructed rather straightforwardly. For instance, for a predator-prey system this result can be achieved through the use of non-monotonic functional response for the predator. However, while formal formulation of such a model is not a problem, the biological justification for such functional responses and models is usually inconclusive. In this note, we explore a conjecture that a multitude of equilibrium states can be caused by an adaptation of animal behaviour to changes of environmental conditions. In order to verify this hypothesis, we consider a simple predator-prey model, which is a straightforward extension of the classic Lotka-Volterra predator-prey model. In this model, we made an intuitively transparent assumption that the prey can change a mode of behaviour in response to the pressure of predation, choosing either "safe" of "risky" (or "business as usual") behaviour. In order to avoid a situation where one of the modes gives an absolute advantage, we introduce the concept of the "cost of a policy" into the model. A simple conceptual two-dimensional predator-prey model, which is minimal with this property, and is not relying on odd functional responses, higher dimensionality or behaviour change for the predator, exhibits two stable co-existing equilibrium states with basins of attraction separated by a separatrix of a saddle point.
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…
Solution equilibrium behind the room-temperature synthesis of nanocrystalline titanium dioxide.
Seisenbaeva, Gulaim A; Daniel, Geoffrey; Nedelec, Jean-Marie; Kessler, Vadim G
2013-04-21
Formation of nanocrystalline and monodisperse TiO2 from a water soluble and stable precursor, ammonium oxo-lactato-titanate, (NH4)8Ti4O4(Lactate)8·4H2O, often referred to as TiBALDH or TALH, is demonstrated to be due to a coordination equilibrium. This compound, individual in the solid state, exists in solution in equilibrium with ammonium tris-lactato-titanate, (NH4)2Ti(Lactate)3 and uniform crystalline TiO2 nanoparticles (anatase) stabilized by surface-capping with lactate ligands. This equilibrium can be shifted towards nano-TiO2via application of a less polar solvent like methanol or ethanol, dilution of the solution, introduction of salts or raising the temperature, and reverted on addition of polar and strongly solvating media such as dimethyl sulfoxide, according to NMR. Aggregation and precipitation of the particles were followed by DLS and could be achieved by a decrease in their surface charge by adsorption of strongly hydrogen-bonding cations, e.g. in solutions of ammonia, ethanolamine or amino acid arginine or by addition of ethanol. The observed equilibrium may be involved in formation of nano-titania on the surface of plant roots exerting chelating organic carboxylate ligands and thus potentially influencing plant interactions.
Non-Equilibrium Molecular Dynamics
NASA Astrophysics Data System (ADS)
Ciccotti, Giovanni; Kapral, Raymond; Sergi, Alessandro
Statistical mechanics provides a well-established link between microscopic equilibrium states and thermodynamics. If one considers systems out of equilibrium, the link between microscopic dynamical properties and non-equilibrium macroscopic states is more difficult to establish [1,2]. For systems lying near equilibrium, linear response theory provides a route to derive linear macroscopic laws and the microscopic expressions for the transport properties that enter the constitutive relations. If the system is displaced far from equilibrium, no fully general theory exists to treat such systems. By restricting consideration to a class of non-equilibrium states which arise from perturbations (linear or non-linear) of an equilibrium state, methods can be developed to treat non-equilibrium states. Furthermore, non-equilibrium molecular dynamics (NEMD) simulation methods can be devised to provide estimates for the transport properties of these systems.
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.
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.
Molecular equilibrium with condensation
NASA Astrophysics Data System (ADS)
Sharp, C. M.; Huebner, W. F.
1990-02-01
Minimization of the Gibbs energy of formation for species of chemical elements and compounds in their gas and condensed phases determines their relative abundances in a mixture in chemical equilibrium. The procedure is more general and more powerful than previous abundance determinations in multiphase astrophysical mixtures. Some results for astrophysical equations of state are presented, and the effects of condensation on opacity are briefly indicated.
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.
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.
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.
Equilibrium of nematic vesicles
NASA Astrophysics Data System (ADS)
Napoli, Gaetano; Vergori, Luigi
2010-11-01
A variational scheme is proposed which allows the derivation of a concise and elegant formulation of the equilibrium equations for closed fluid membranes, endowed with a nematic microstructure. The nematic order is described by an in-plane nematic director and a degree of orientation, as customary in the theory of uniaxial nematics. The only constitutive ingredient in this scheme is a free-energy density which depends on the vesicle geometry and order parameters. The stress and the couple stress tensors related to this free-energy density are provided. As an application of the proposed scheme, a certain number of special theories are deduced: soap bubbles, lipid vesicles, chiral and achiral nematic membranes, and nematics on curved substrates.
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.
Solution equilibrium behind the room-temperature synthesis of nanocrystalline titanium dioxide
NASA Astrophysics Data System (ADS)
Seisenbaeva, Gulaim A.; Daniel, Geoffrey; Nedelec, Jean-Marie; Kessler, Vadim G.
2013-03-01
Formation of nanocrystalline and monodisperse TiO2 from a water soluble and stable precursor, ammonium oxo-lactato-titanate, (NH4)8Ti4O4(Lactate)8.4H2O, often referred to as TiBALDH or TALH, is demonstrated to be due to a coordination equilibrium. This compound, individual in the solid state, exists in solution in equilibrium with ammonium tris-lactato-titanate, (NH4)2Ti(Lactate)3 and uniform crystalline TiO2 nanoparticles (anatase) stabilized by surface-capping with lactate ligands. This equilibrium can be shifted towards nano-TiO2via application of a less polar solvent like methanol or ethanol, dilution of the solution, introduction of salts or raising the temperature, and reverted on addition of polar and strongly solvating media such as dimethyl sulfoxide, according to NMR. Aggregation and precipitation of the particles were followed by DLS and could be achieved by a decrease in their surface charge by adsorption of strongly hydrogen-bonding cations, e.g. in solutions of ammonia, ethanolamine or amino acid arginine or by addition of ethanol. The observed equilibrium may be involved in formation of nano-titania on the surface of plant roots exerting chelating organic carboxylate ligands and thus potentially influencing plant interactions.Formation of nanocrystalline and monodisperse TiO2 from a water soluble and stable precursor, ammonium oxo-lactato-titanate, (NH4)8Ti4O4(Lactate)8.4H2O, often referred to as TiBALDH or TALH, is demonstrated to be due to a coordination equilibrium. This compound, individual in the solid state, exists in solution in equilibrium with ammonium tris-lactato-titanate, (NH4)2Ti(Lactate)3 and uniform crystalline TiO2 nanoparticles (anatase) stabilized by surface-capping with lactate ligands. This equilibrium can be shifted towards nano-TiO2via application of a less polar solvent like methanol or ethanol, dilution of the solution, introduction of salts or raising the temperature, and reverted on addition of polar and strongly solvating
Development of safe mechanism for surgical robots using equilibrium point control method.
Park, Shinsuk; Lim, Hokjin; Kim, Byeong-sang; Song, Jae-bok
2006-01-01
This paper introduces a novel mechanism for surgical robotic systems to generate human arm-like compliant motion. The mechanism is based on the idea of the equilibrium point control hypothesis which claims that multi-joint limb movements are achieved by shifting the limbs' equilibrium positions defined by neuromuscular activity. The equilibrium point control can be implemented on a robot manipulator by installing two actuators at each joint of the manipulator, one to control the joint position, and the other to control the joint stiffness. This double-actuator mechanism allows us to arbitrarily manipulate the stiffness (or impedance) of a robotic manipulator as well as its position. Also, the force at the end-effector can be estimated based on joint stiffness and joint angle changes without using force transducers. A two-link manipulator and a three-link manipulator with the double-actuator units have been developed, and experiments and simulation results show the potential of the proposed approach. By creating the human arm-like behavior, this mechanism can improve the performance of robot manipulators to execute stable and safe movement in surgical environments by using a simple control scheme.
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.
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.
Equilibrium Policy Proposals with Abstentions.
1981-05-01
AB I I I EQUILIBRIUM POLICY PROPOSALS WITH ABSTENTIONS* by Peter Coughlin** 1. Introduction Spatial analyses of economic policy formation in elections...alternative in S at which there is a local equilibrium when the incumbent must defend the status quo. 5. Applications to Related Spatial Voting Models...York: Holt, Rinehart and Winston. Hestenes, M. [19751, Optimization Theoy, New York: Wiley. Hinich, M. [1977], " Equilibrium in Spatial Voting: The Median
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.
Topologically protected modes in non-equilibrium stochastic systems
Murugan, Arvind; Vaikuntanathan, Suriyanarayanan
2017-01-01
Non-equilibrium driving of biophysical processes is believed to enable their robust functioning despite the presence of thermal fluctuations and other sources of disorder. Such robust functions include sensory adaptation, enhanced enzymatic specificity and maintenance of coherent oscillations. Elucidating the relation between energy consumption and organization remains an important and open question in non-equilibrium statistical mechanics. Here we report that steady states of systems with non-equilibrium fluxes can support topologically protected boundary modes that resemble similar modes in electronic and mechanical systems. Akin to their electronic and mechanical counterparts, topological-protected boundary steady states in non-equilibrium systems are robust and are largely insensitive to local perturbations. We argue that our work provides a framework for how biophysical systems can use non-equilibrium driving to achieve robust function. PMID:28071644
Topologically protected modes in non-equilibrium stochastic systems
NASA Astrophysics Data System (ADS)
Murugan, Arvind; Vaikuntanathan, Suriyanarayanan
2017-01-01
Non-equilibrium driving of biophysical processes is believed to enable their robust functioning despite the presence of thermal fluctuations and other sources of disorder. Such robust functions include sensory adaptation, enhanced enzymatic specificity and maintenance of coherent oscillations. Elucidating the relation between energy consumption and organization remains an important and open question in non-equilibrium statistical mechanics. Here we report that steady states of systems with non-equilibrium fluxes can support topologically protected boundary modes that resemble similar modes in electronic and mechanical systems. Akin to their electronic and mechanical counterparts, topological-protected boundary steady states in non-equilibrium systems are robust and are largely insensitive to local perturbations. We argue that our work provides a framework for how biophysical systems can use non-equilibrium driving to achieve robust function.
Topologically protected modes in non-equilibrium stochastic systems.
Murugan, Arvind; Vaikuntanathan, Suriyanarayanan
2017-01-10
Non-equilibrium driving of biophysical processes is believed to enable their robust functioning despite the presence of thermal fluctuations and other sources of disorder. Such robust functions include sensory adaptation, enhanced enzymatic specificity and maintenance of coherent oscillations. Elucidating the relation between energy consumption and organization remains an important and open question in non-equilibrium statistical mechanics. Here we report that steady states of systems with non-equilibrium fluxes can support topologically protected boundary modes that resemble similar modes in electronic and mechanical systems. Akin to their electronic and mechanical counterparts, topological-protected boundary steady states in non-equilibrium systems are robust and are largely insensitive to local perturbations. We argue that our work provides a framework for how biophysical systems can use non-equilibrium driving to achieve robust function.
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.
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
Equilibrium and non-equilibrium cluster phases in colloids with competing interactions.
Mani, Ethayaraja; Lechner, Wolfgang; Kegel, Willem K; Bolhuis, Peter G
2014-07-07
The phase behavior of colloids that interact via competing interactions - short-range attraction and long-range repulsion - is studied by computer simulation. In particular, for a fixed strength and range of repulsion, the effect of the strength of an attractive interaction (ε) on the phase behavior is investigated at various colloid densities (ρ). A thermodynamically stable equilibrium colloidal cluster phase, consisting of compact crystalline clusters, is found below the fluid-solid coexistence line in the ε-ρ parameter space. The mean cluster size is found to linearly increase with the colloid density. At large ε and low densities, and at small ε and high densities, a non-equilibrium cluster phase, consisting of elongated Bernal spiral-like clusters, is observed. Although gelation can be induced either by increasing ε at constant density or vice versa, the gelation mechanism is different in either route. While in the ρ route gelation occurs via a glass transition of compact clusters, gelation in the ε route is characterized by percolation of elongated clusters. This study both provides the location of equilibrium and non-equilibrium cluster phases with respect to the fluid-solid coexistence, and reveals the dependencies of the gelation mechanism on the preparation route.
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…
Equilibrium states for hyperbolic potentials
NASA Astrophysics Data System (ADS)
Ramos, Vanessa; Viana, Marcelo
2017-02-01
We prove the existence of finitely many ergodic equilibrium states for local homeomorphisms and hyperbolic potentials. We also deal with partially hyperbolic skew-products over non-uniformly expanding maps with uniform contraction on the fibre. For these systems we prove the existence and finiteness of the equilibrium states associated with a class of Hölder continuous potentials.
Thermodynamic efficiency out of equilibrium
NASA Astrophysics Data System (ADS)
Sivak, David; Crooks, Gavin
2011-03-01
Molecular-scale machines typically operate far from thermodynamic equilibrium, limiting the applicability of equilibrium statistical mechanics to understand their efficiency. Thermodynamic length analysis relates a non-equilibrium property (dissipation) to equilibrium properties (equilibrium fluctuations and their relaxation time). Herein we demonstrate that the thermodynamic length framework follows directly from the assumptions of linear response theory. Uniting these two frameworks provides thermodynamic length analysis a firmer statistical mechanical grounding, and equips linear response theory with a metric structure to facilitate the prediction and discovery of optimal (minimum dissipation) paths in complicated free energy landscapes. To explore the applicability of this theoretical framework, we examine its accuracy for simple bistable systems, parametrized to model single-molecule force-extension experiments. Through analytic derivation of the equilibrium fluctuations and numerical calculation of the dissipation and relaxation time, we verify that thermodynamic length analysis (though derived in a near-equilibrium limit) provides a strikingly good approximation even far from equilibrium, and thus provides a useful framework for understanding molecular motor efficiency.
Hydraulic non-equilibrium during infiltration induced by structural connectivity
NASA Astrophysics Data System (ADS)
Schlüter, S.; Vanderborght, J.; Vogel, H.-J.
2012-04-01
Water infiltration into heterogeneous, structured soil leads to hydraulic non-equilibrium across the infiltration front. That is the water content and water potential is not in equilibrium according to some static water retention curve. The water content increases more rapidly in more conductive regions followed by a slow relaxation towards an equilibrium state. An extreme case is preferential infiltration into macro-pores. As flow paths adapt to the structural heterogeneity of the subsurface, there is a direct link between structure and non-equilibrium. The aim of our study is to develop an upscaled description of water dynamics which conserves the macroscopic effects of non-equilibrium and which can be linked to structural properties of the material. However, this relationship cannot be rigorously examined without an upscaling approach that conserves non-equilibrium during averaging of state variables. We achieve this with a novel approach, that is based on flux-weighted averaging of hydraulic potential, and compare its performance to existing averaging approaches by means of infiltration simulations. Further, we set up some meaningful indicators of hydraulic non-equilibrium that can be easily compared to morphological characteristics of the infiltration front. These methods provide a sound basis to assess the impact of structural connectivity on hydraulic non-equilibrium. We generate several realizations of two-dimensional random fields originating from three heterogeneity models with distinct differences in connectivity of high-K areas and conduct infiltration simulations with them. Our results indicate, that an increased isotropic, short-range connectivity reduces non-equilibrium, whereas anisotropic, macropore-like structures enforce it. We observed a good agreement between front morphology and upscaled non-equilibrium. Our findings encourage to use flux-weighted potentials for upscaling of state variables during transient conditions. We demonstrate, that
Hydraulic non-equilibrium during infiltration induced by structural connectivity
NASA Astrophysics Data System (ADS)
Schlüter, S.; Vogel, H.
2011-12-01
Water infiltration into heterogeneous, structured soil leads to hydraulic non-equilibrium across the infiltration front. That is the water content and water potential is not in equilibrium according to some static water retention curve. The water content increases more rapidly in more conductive regions followed by a slow relaxation towards an equilibrium state. An extreme case is preferential infiltration into macro-pores. As flowpaths adapt to the structural heterogeneity of the subsurface, there is a direct link between structure and non-equilibrium. The aim of our study is to develop an upscaled description of water dynamics which conserves the macroscopic effects of non-equilibrium and which can be linked to structural properties of the material. However, this relationship cannot be rigorously examined without an upscaling approach that conserves non-equilibrium during averaging of state variables. We achieve this with a novel approach, that is based on flux-weighted averaging of hydraulic potential, and compare its performance to existing averaging approaches by means of infiltration simulations. Further, we set up some meaningful indicators of hydraulic non-equilibrium that can be easily compared to morphological characteristics of the infiltration front. These methods provide a sound basis to assess the impact of structural connectivity on hydraulic non-equilibrium. We generate several realizations of two-dimensional random fields originating from three heterogeneity models with distinct differences in connectivity of high-K areas and conduct infiltration simulations with them. Our results indicate, that an increased isotropic, short-range connectivity reduces non-equilibrium, whereas anisotropic, macropore-like structures enforce it. We observed a good agreement between front morphology and upscaled non-equilibrium. Our findings encourage to use flux-weighted potentials for upscaling of state variables during transient conditions. We demonstrate, that this
Magnetic Images & A Novel Stable Ferro-Magnetic Suspension
NASA Astrophysics Data System (ADS)
Zhang, Huaizhou
In 2010 the Physics Nobel prize was awarded to A.K. Geim and K. Novoselov [1], famous for their spectacular demonstrations of diamagnetically levitated living animals. My MS research is an investigation to develop a novel magnetic suspension capable of operating under ambient conditions without any cryogenics. The physical problem is to freely suspended an object, the proof mass (PM) in stable equilibrium under the combined actions of gravity and magnetic forces. Earshaws's theorem enunciated in 1842 prohibits such a possibility. After the discovery of diamagnetism by Michael Faraday, Lord Kelvin predicted that diamagnetic systems are immune to this theorem. As the Bohr_Van Leeuwen's theorem proved that the origin of magnetism is quantum mechanical, however, many aspects of magnetic behavior can be treated classically. Recently, Berry, Geim and collaborators [Eur J Phy, 18, 307 (1997); J. of Appld. Phys 87, 6200 (2000)] showed that stability of a diamagnetic PM, or a magnetized PM. The proof masses in this work can be even be unmagnetized still we show that with an appropriate diamagnetic stabilizer equilibrium is achieved along all three Cartesian axes. The forces follow the Bio-Savart field due to localized current loops but at short distances are well represented by algebraic power laws. Experimental procedures for direct measurements of the magnetic image forces and physical modeling will be discussed.
Non-equilibrium supramolecular polymerization.
Sorrenti, Alessandro; Leira-Iglesias, Jorge; Markvoort, Albert J; de Greef, Tom F A; Hermans, Thomas M
2017-03-28
Supramolecular polymerization has been traditionally focused on the thermodynamic equilibrium state, where one-dimensional assemblies reside at the global minimum of the Gibbs free energy. The pathway and rate to reach the equilibrium state are irrelevant, and the resulting assemblies remain unchanged over time. In the past decade, the focus has shifted to kinetically trapped (non-dissipative non-equilibrium) structures that heavily depend on the method of preparation (i.e., pathway complexity), and where the assembly rates are of key importance. Kinetic models have greatly improved our understanding of competing pathways, and shown how to steer supramolecular polymerization in the desired direction (i.e., pathway selection). The most recent innovation in the field relies on energy or mass input that is dissipated to keep the system away from the thermodynamic equilibrium (or from other non-dissipative states). This tutorial review aims to provide the reader with a set of tools to identify different types of self-assembled states that have been explored so far. In particular, we aim to clarify the often unclear use of the term "non-equilibrium self-assembly" by subdividing systems into dissipative, and non-dissipative non-equilibrium states. Examples are given for each of the states, with a focus on non-dissipative non-equilibrium states found in one-dimensional supramolecular polymerization.
Technology Transfer Automated Retrieval System (TEKTRAN)
Adult stable flies feed on the blood of humans, pets and livestock, inflicting painful bites. Stable flies need one and sometimes two bloodmeals each day to develop their eggs. Unlike mosquitoes where only the females bloodfeed, both male and female stable flies require blood to reproduce. Stable fl...
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.
Interregional equilibrium with heterogeneous labor.
Michel, P; Perrot, A; Thisse J-f
1996-02-01
"The impact of labor migration on interregional equilibrium is studied when workers are heterogeneous in productivity and regional mobility. The skilled respond to market disequilibrium by moving into the most attractive region. The unskilled are immobile in the short-run and move with the skilled in the long-run. Both regions have a neoclassical production function affected by an externality depending on the number of skilled. Workers move according to the utility differential when regional amenities vary with population or according to the wage differential. The equilibrium pattern depends on the unskilled's mobility and on migration incentives. Typically, regional imbalance characterizes the equilibrium which is often suboptimal."
The nonlinear model for emergence of stable conditions in gas mixture in force field
NASA Astrophysics Data System (ADS)
Kalutskov, Oleg; Uvarova, Liudmila
2016-06-01
The case of M-component liquid evaporation from the straight cylindrical capillary into N - component gas mixture in presence of external forces was reviewed. It is assumed that the gas mixture is not ideal. The stable states in gas phase can be formed during the evaporation process for the certain model parameter valuesbecause of the mass transfer initial equationsnonlinearity. The critical concentrations of the resulting gas mixture components (the critical component concentrations at which the stable states occur in mixture) were determined mathematically for the case of single-component fluid evaporation into two-component atmosphere. It was concluded that this equilibrium concentration ratio of the mixture components can be achieved by external force influence on the mass transfer processes. It is one of the ways to create sustainable gas clusters that can be used effectively in modern nanotechnology.
Nonexistence of equilibrium states at absolute negative temperatures
NASA Astrophysics Data System (ADS)
Romero-Rochín, Víctor
2013-08-01
We show that states of macroscopic systems with purported absolute negative temperatures are not stable under small, yet arbitrary, perturbations. We prove the previous statement using the fact that, in equilibrium, the entropy takes its maximum value. We discuss that, while Ramsey theoretical reformulation of the second law for systems with negative temperatures is logically correct, it must be a priori assumed that those states are in thermodynamic equilibrium. Since we argue that those states cannot occur, reversible processes are impossible, and, thus, Ramsey identification of absolute negative temperatures is untenable.
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 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)
Simulations for Teaching Chemical Equilibrium
NASA Astrophysics Data System (ADS)
Huddle, Penelope A.; White, Margaret Dawn; Rogers, Fiona
2000-07-01
This paper outlines a systematic approach to teaching chemical equilibrium using simulation experiments that address most known alternate conceptions in the topic. Graphs drawn using the data from the simulations are identical to those obtained using real experimental data for reactions that go to equilibrium. This allows easy mapping of the analogy to the target. The requirements for the simulations are simple and inexpensive, making them accessible to even the poorest schools. The simulations can be adapted for all levels, from pupils who are first encountering equilibrium through students in tertiary education to qualified teachers who have experienced difficulty in teaching the topic. The simulations were piloted on four very different audiences. Minor modifications were then made before the Equilibrium Games as reported in this paper were tested on three groups of subjects: a Grade 12 class, college students, and university Chemistry I students. Marked improvements in understanding of the concept were shown in two of the three sets of subjects.
Achieving fast and stable failure detection in WDM Networks
NASA Astrophysics Data System (ADS)
Gao, Donghui; Zhou, Zhiyu; Zhang, Hanyi
2005-02-01
In dynamic networks, the failure detection time takes a major part of the convergence time, which is an important network performance index. To detect a node or link failure in the network, traditional protocols, like Hello protocol in OSPF or RSVP, exchanges keep-alive messages between neighboring nodes to keep track of the link/node state. But by default settings, it can get a minimum detection time in the measure of dozens of seconds, which can not meet the demands of fast network convergence and failure recovery. When configuring the related parameters to reduce the detection time, there will be notable instability problems. In this paper, we analyzed the problem and designed a new failure detection algorithm to reduce the network overhead of detection signaling. Through our experiment we found it is effective to enhance the stability by implicitly acknowledge other signaling messages as keep-alive messages. We conducted our proposal and the previous approaches on the ASON test-bed. The experimental results show that our algorithm gives better performances than previous schemes in about an order magnitude reduction of both false failure alarms and queuing delay to other messages, especially under light traffic load.
Stable topological insulators achieved using high energy electron beams
Zhao, Lukas; Konczykowski, Marcin; Deng, Haiming; Korzhovska, Inna; Begliarbekov, Milan; Chen, Zhiyi; Papalazarou, Evangelos; Marsi, Marino; Perfetti, Luca; Hruban, Andrzej; Wołoś, Agnieszka; Krusin-Elbaum, Lia
2016-01-01
Topological insulators are potentially transformative quantum solids with metallic surface states which have Dirac band structure and are immune to disorder. Ubiquitous charged bulk defects, however, pull the Fermi energy into the bulk bands, denying access to surface charge transport. Here we demonstrate that irradiation with swift (∼2.5 MeV energy) electron beams allows to compensate these defects, bring the Fermi level back into the bulk gap and reach the charge neutrality point (CNP). Controlling the beam fluence, we tune bulk conductivity from p- (hole-like) to n-type (electron-like), crossing the Dirac point and back, while preserving the Dirac energy dispersion. The CNP conductance has a two-dimensional character on the order of ten conductance quanta and reveals, both in Bi2Te3 and Bi2Se3, the presence of only two quantum channels corresponding to two topological surfaces. The intrinsic quantum transport of the topological states is accessible disregarding the bulk size. PMID:26961901
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.
Relevance of equilibrium in multifragmentation
Furuta, Takuya; Ono, Akira
2009-01-15
The relevance of equilibrium in a multifragmentation reaction of very central {sup 40}Ca + {sup 40}Ca collisions at 35 MeV/nucleon is investigated by using simulations of antisymmetrized molecular dynamics (AMD). Two types of ensembles are compared. One is the reaction ensemble of the states at each reaction time t in collision events simulated by AMD, and the other is the equilibrium ensemble prepared by solving the AMD equation of motion for a many-nucleon system confined in a container for a long time. The comparison of the ensembles is performed for the fragment charge distribution and the excitation energies. Our calculations show that there exists an equilibrium ensemble that well reproduces the reaction ensemble at each reaction time t for the investigated period 80{<=}t{<=}300 fm/c. However, there are some other observables that show discrepancies between the reaction and equilibrium ensembles. These may be interpreted as dynamical effects in the reaction. The usual static equilibrium at each instant is not realized since any equilibrium ensemble with the same volume as that of the reaction system cannot reproduce the fragment observables.
Magnetotelluric Data, Stable Distributions and Stable Regression
NASA Astrophysics Data System (ADS)
Chave, A. D.
2013-12-01
The author has noted for many years that the residuals from robust or bounded influence estimates of the magnetotelluric response function are systematically long tailed compared to a Gaussian or Rayleigh distribution. Consequently, the standard statistical model of a Gaussian core contaminated by a fraction of outlying data is not really valid. However, the typical result is an improvement on ordinary least squares, and has become standard in the electromagnetic induction community. A recent re-evaluation of the statistics of magnetotelluric response function estimation has shown that, in almost all cases, the residuals are alpha stable rather than Gaussian. Alpha stable distributions are characterized by four parameters: a shape parameter lying on (0, 2], a skewness parameter, a scale parameter and a location parameter, and cannot be expressed in closed form except for a few special cases. When the shape parameter is 2, the result is Gaussian, but when it is smaller the resulting distribution has infinite variance. Typical magnetotelluric residuals are alpha stable with a shape parameter lying between 1 and 2. This suggests that robust methods improve response function estimates by eliminating data corresponding to the largest stable residuals while leaving the bulk of the population alone. A better statistical approach is based on stable regression that directly accommodates the actual residual distribution without eliminating the most extreme ones. This paper will introduce such an algorithm, and illustrate its functionality with a variety of magnetotelluric data. Further work remains to produce a robust stable regression algorithm that will eliminate real outliers such as lightning strikes or instrument problems without affecting the bulk stable population. Stable distributions are intimately associated with fractional derivative physical processes. Since the Maxwell equations and the constitutive relations pertaining to the earth do not contain any fractional
From interacting particles to equilibrium statistical ensembles
NASA Astrophysics Data System (ADS)
Ilievski, Enej; Quinn, Eoin; Caux, Jean-Sébastien
2017-03-01
We argue that a particle language provides a conceptually simple framework for the description of anomalous equilibration in isolated quantum systems. We address this paradigm in the context of integrable models, which are those where particles scatter completely elastically and are stable against decay. In particular, we demonstrate that a complete description of equilibrium ensembles for interacting integrable models requires a formulation built from the mode occupation numbers of the underlying particle content, mirroring the case of noninteracting particles. This yields an intuitive physical interpretation of generalized Gibbs ensembles, and reconciles them with the microcanonical ensemble. We explain how previous attempts to identify an appropriate ensemble overlooked an essential piece of information, and provide explicit examples in the context of quantum quenches.
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
Mineral equilibrium in fractionated nebular systems
NASA Technical Reports Server (NTRS)
Wood, John A.; Hashimoto, Akihiko
1993-01-01
We investigated the equilibrium mineral assemblages in chemically fractionated nebular systems, using a computer routine that finds the set of minerals and gases which minimizes the Gibbs free energy of a system with stipulated elemental abundances. Diagrams are presented showing the equilibrium mineralogy, as a function of temperature (400-2300 K), for unfractionated solar material and five fractionated systems. The fractionated systems were defined by mixing, in various proportions, the following four volatility components that solar material can be divided into: refractory dust, carbonaceous matter, ices, and H2 gas. Dust enrichment is seen to increase temperatures of condensation/evaporation and the Fe(2+) content of mafic minerals and to permit existence of stable melt phases. Enrichment of dust and organic matter produces mineral assemblages that are similar in many ways to those of enstatite chondrites, but with mafic minerals that are far more reduced than those in primitive enstatite chondrites. Enrichment of dust, organics, and ices leads to highly ferrous mineralogies even at the highest temperatures but does not predict the stability of hydrous phases above about 450 K.
Kinetic and equilibrium measurements of coal drying
Heller, A.; Elliott, G.R.B.
1980-01-01
The retention, attachment, and release of water (sorption, adsorption, and desorption) in Fruitland subbituminous coal are shown to be very complex phenomena. The vapor pressure and thermodynamic activity of water in the coal at about 315 K vary sharply with composition. Removal of 60% of the water initially present reduces the vapor pressure by about 60%. The total moisture content of saturated coal also varies with temperature. A 10 K rise in temperature reduces the sorbed water by about 8%. There is strong hysteresis in the sorption behavior; water which is desorbed by reducing the vapor pressure over a coal sample is not fully replaced by adsorption when the vapor pressure is returned to its original level. These measurements of desorption and adsorption reflect stable and metastable equilibria. Kinetic measurements are reported for approach to a new equilibrium if the vapor pressure over the coal is reduced. The kinetic measurements reflect the shape of the pores while equilibrium vapor pressures reflect how tightly the water is bound in the pores. Both types of measurement show changes in behavior at the same compositions. Implications of these results for UCG are discussed.
NASA Astrophysics Data System (ADS)
Sousa, Tânia; Domingos, Tiago
2006-11-01
We develop a unified conceptual and mathematical structure for equilibrium econophysics, i.e., the use of concepts and tools of equilibrium thermodynamics in neoclassical microeconomics and vice versa. Within this conceptual structure the results obtained in microeconomic theory are: (1) the definition of irreversibility in economic behavior; (2) the clarification that the Engel curve and the offer curve are not descriptions of real processes dictated by the maximization of utility at constant endowment; (3) the derivation of a relation between elasticities proving that economic elasticities are not all independent; (4) the proof that Giffen goods do not exist in a stable equilibrium; (5) the derivation that ‘economic integrability’ is equivalent to the generalized Le Chatelier principle and (6) the definition of a first order phase transition, i.e., a transition between separate points in the utility function. In thermodynamics the results obtained are: (1) a relation between the non-dimensional isothermal and adiabatic compressibilities and the increase or decrease in the thermodynamic potentials; (2) the distinction between mathematical integrability and optimization behavior and (3) the generalization of the Clapeyron equation.
Non-equilibrium freezing behaviour of aqueous systems.
MacKenzie, A P
1977-03-29
The tendencies to non-equilibrium freezing behaviour commonly noted in representative aqueous systems derive from bulk and surface properties according to the circumstances. Supercooling and supersaturation are limited by heterogeneous nucleation in the presence of solid impurities. Homogeneous nucleation has been observed in aqueous systems freed from interfering solids. Once initiated, crystal growth is ofter slowed and, very frequently, terminated with increasing viscosity. Nor does ice first formed always succeed in assuming its most stable crystalline form. Many of the more significant measurements on a given systeatter permitting the simultaneous representation of thermodynamic and non-equilibrium properties. The diagram incorporated equilibrium melting points, heterogeneous nucleation temperatures, homogeneous nucleation temperatures, glass transition and devitrification temperatures, recrystallization temperatures, and, where appropriate, solute solubilities and eutectic temperatures. Taken together, the findings on modle systems aid the identification of the kinetic and thermodynamic factors responsible for the freezing-thawing survival of living cells.
Angina Pectoris (Stable Angina)
... Peripheral Artery Disease Venous Thromboembolism Aortic Aneurysm More Angina Pectoris (Stable Angina) Updated:Sep 19,2016 You may have heard the term “angina pectoris” or “stable angina” in your doctor’s office, but ...
Stable electroosmotically driven actuators
NASA Astrophysics Data System (ADS)
Sritharan, Deepa; Motsebo, Mylene; Tumbic, Julia; Smela, Elisabeth
2013-04-01
We have previously presented "nastic" actuators based on electroosmotic (EO) pumping of fluid in microchannels using high electric fields for potential application in soft robotics. In this work we address two challenges facing this technology: applying EO to meso-scale devices and the stability of the pumping fluid. The hydraulic pressure achieved by EO increases with as 1/d2, where d is the depth of the microchannel, but the flow rate (which determines the stroke and the speed) is proportional to nd, where n is the number of channels. Therefore to get high force and high stroke the device requires a large number of narrow channels, which is not readily achievable using standard microfabrication techniques. Furthermore, for soft robotics the structure must be soft. In this work we present a method of fabricating a three-dimensional porous elastomer to serve as the array of channels based on a sacrificial sugar scaffold. We demonstrate the concept by fabricating small pumps. The flexible devices were made from polydimethylsiloxane (PDMS) and comprise the 3D porous elastomer flanked on either side by reservoirs containing electrodes. The second issue addressed here involves the pumping fluid. Typically, water is used for EO, but water undergoes electrolysis even at low voltages. Since EO takes place at kV, these systems must be open to release the gases. We have recently reported that propylene carbonate (PC) is pumped at a comparable rate as water and is also stable for over 30 min at 8 kV. Here we show that PC is, however, degraded by moisture, so future EO systems must prevent water from reaching the PC.
Invariant manifolds around artificial equilibrium points for low-thrust propulsion spacecraft
NASA Astrophysics Data System (ADS)
Lei, Hanlun; Xu, Bo
2017-04-01
Low-thrust propulsion is incorporated into circular restricted three-body problem to balance the gravitational and centrifugal forces, and then artificial equilibrium points can be generated. The linear dynamics indicates that there are stable and unstable artificial equilibrium points. Around the unstable artificial equilibrium points, there are center and hyperbolic invariant manifolds. In this work, invariant manifolds around artificial equilibrium points are expressed as formal series of amplitudes corresponding to hyperbolic and center dynamics, and high-order series solutions are constructed up to an arbitrary order. By taking advantage of the series expansions constructed, the motions around unstable artificial equilibrium points can be parameterized. In order to check the validity, the practical convergence of series solutions truncated at different orders is considered. Finally, series expansions of invariant manifolds are applied to designing transfer trajectories from the primary to periodic orbits around artificial equilibrium points which are located inside L1 and beyond L2 points.
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.
NASA Astrophysics Data System (ADS)
Hou, X. D.; Alvarez, C. L. M.; Jennett, N. M.
2017-02-01
Instrumented indentation testing (IIT) at elevated temperatures has proved to be a useful tool to study plastic and elastic deformation and understand the performance of material components at (or nearer to) the actual temperatures experienced in-service. The value of elevated temperature IIT data, however, depends on the ability not only to achieve a stable, isothermal indentation contact at thermal equilibrium when taking data, but to be able to assign a valid temperature to that contact (and so to the data). The most common method found in the current literature is to use the calculated thermal drift rate as an indicator, but this approach has never been properly validated. This study proves that using the thermal drift rate to determine isothermal contact may lead to large errors in the determination of the real contact temperature. Instead, a more sensitive and validated method is demonstrated, based upon using the indenter tip and the tip heater control thermocouple as a reproducible and calibrated contact temperature sensor. A simple calibration procedure is described, along with step by step guidance to establish an isothermal contact at a known temperature under thermal equilibrium when conducting elevated temperature IIT experiments.
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
Equilibrium in a Production Economy
Chiarolla, Maria B.; Haussmann, Ulrich G.
2011-06-15
Consider a closed production-consumption economy with multiple agents and multiple resources. The resources are used to produce the consumption good. The agents derive utility from holding resources as well as consuming the good produced. They aim to maximize their utility while the manager of the production facility aims to maximize profits. With the aid of a representative agent (who has a multivariable utility function) it is shown that an Arrow-Debreu equilibrium exists. In so doing we establish technical results that will be used to solve the stochastic dynamic problem (a case with infinite dimensional commodity space so the General Equilibrium Theory does not apply) elsewhere.
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.…
Equilibrium Principles: A Game for Students
NASA Astrophysics Data System (ADS)
Edmonson, Lionel J., Jr.; Lewis, Don L.
1999-04-01
The laboratory exercise is a game using marked sugar cubes as dice. The game emphasizes the dynamic character of equilibrium. Forward and reverse rate-constant values are used to calculate an equilibrium constant and to predict equilibrium populations. Predicted equilibrium populations are compared with experimental results.
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.
Thermodynamic theory of equilibrium fluctuations
Mishin, Y.
2015-12-15
The postulational basis of classical thermodynamics has been expanded to incorporate equilibrium fluctuations. The main additional elements of the proposed thermodynamic theory are the concept of quasi-equilibrium states, a definition of non-equilibrium entropy, a fundamental equation of state in the entropy representation, and a fluctuation postulate describing the probability distribution of macroscopic parameters of an isolated system. Although these elements introduce a statistical component that does not exist in classical thermodynamics, the logical structure of the theory is different from that of statistical mechanics and represents an expanded version of thermodynamics. Based on this theory, we present a regular procedure for calculations of equilibrium fluctuations of extensive parameters, intensive parameters and densities in systems with any number of fluctuating parameters. The proposed fluctuation formalism is demonstrated by four applications: (1) derivation of the complete set of fluctuation relations for a simple fluid in three different ensembles; (2) fluctuations in finite-reservoir systems interpolating between the canonical and micro-canonical ensembles; (3) derivation of fluctuation relations for excess properties of grain boundaries in binary solid solutions, and (4) derivation of the grain boundary width distribution for pre-melted grain boundaries in alloys. The last two applications offer an efficient fluctuation-based approach to calculations of interface excess properties and extraction of the disjoining potential in pre-melted grain boundaries. Possible future extensions of the theory are outlined.
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…
Application of non-equilibrium plasmas in treatment of wool fibers and seeds
NASA Astrophysics Data System (ADS)
Petrović, Zoran
2003-10-01
While large effort is under way to achieve stable, large area, non-equilibrium plasma reactors operating at atmospheric pressure we should still consider application of low pressure reactors, which provide well defined, easily controlled reactive plasmas. Therefore, the application of low pressure rf plasmas for the treatment of wool and seed was investigated. The studies were aimed at establishing optimal procedure to achieve better wettability, dyeability and printability of wool. Plasma treatment led to a modification of wool fiber topography and formation of new polar functional groups inducing the increase of wool hydrophylicity. Plasma activation of fiber surface was also used to achieve better binding of biopolymer chitosan to wool in order to increase the content of favorable functional groups and thus improving sorption properties of recycled wool fibers for heavy metal ions and acid dyes. In another study, the increase of germination percentage of seeds induced by plasmas was investigated. We have selected dry (unimbibed) Empress tree seeds (Paulownia tomentosa Steud.). Empress tree seed has been studied extensively and its mechanism of germination is well documented. Germination of these seeds is triggered by light in a limited range of wavelengths. Interaction between activated plasma particles and seed, inside the plasma reactor, leads to changes in its surface topography, modifies the surface layer and increases the active surface area. Consequently, some bioactive nitrogeneous compounds could be bound to the activated surface layer causing the increment of germination percentage.
Equilibrium of nucleotides in the dogfish brain.
Andjus, Radoslav K; Dzakula, Zeljko; Marjanović, Marina
2005-06-01
In the past, the results of experiments on the time course of concentration changes of adenylates, phosphocreatine, and free creatine in muscle appeared compatible with an equilibrium hypothesis involving only the Lohmann and the myokinase reactions. Other reports, however, denied the applicability of the equilibrium hypothesis to the same tissue. The controversy may have been due to the high probability of experimental errors since time sampling was performed at second intervals. We presently test the hypothesis in the living brain of the small-spotted dogfish shark (Scyliorhinus canicula), an animal-model allowing for timing of sampling at hourly intervals. According to our earlier work, the dogfish shark can easily be resuscitated 8.2 h on average after being brought into the state of "suspended animation" at 0 degree C body temperature and exposed, out of water, to an atmosphere of nitrogen gas. To obtain a complete mathematical description of the time course of concentration changes of brain adenylates and phosphocreatine, we devised a kinetic model based on principles of classical multicompartmental analysis and biochemical kinetics. Model testing of the equilibrium hypothesis resulted in very good agreement between the hypothesis and our experimental data. Time-course modeling, achieved by simultaneously fitting the time series of our data by the set of four equations constituting our model resulted in an excellent agreement between data points and the computed curves. Finally, modeling of the depletion profiles of brain energy status concerning three of its descriptors (energy charge, total adenylate, and primary energy stores expressed in high-energy phosphate equivalents) allowed for a correlation to be established between energy status and the "revival time," a valuable physiological descriptor of tolerance.
On feedback and stable price adjustment mechanisms
NASA Astrophysics Data System (ADS)
Fernandez-Anaya, Guillermo; Alvarez-Ramirez, Jose; Ibarra-Valdez, Carlos
2007-04-01
Given an excess demand function of an economy, say Z(p), a stable price adjustment mechanism (SPAM) guarantees convergence of solution path p(t,p0) to an equilibrium peq solution of Z(p)=0. Besides, all equilibrium points of Z(p) are asymptotically stable. Some SPAMs have been proposed, including Newton and transpose Jacobian methods. Despite this powerful stability property of SPAMs, their acceptation in the economics community has been limited by a lack of interpretation. This paper focuses on this issue. Specifically, feedback control theory is used to link SPAMs and price dynamics models with control inputs, which match the economically intuitive Walrasian Hypothesis (i.e., prices change with excess demand sign). Under mild conditions, it is shown the existence of a feedback function that transforms the price dynamics into a desired SPAM. Hence, a SPAM is interpreted as a fundamental (e.g., Walrasian) price dynamics under the action of a feedback function aimed to stabilize the equilibrium set of the excess demand function.
MEERSCHAERT, MARK M.; STRAKA, PETER
2013-01-01
The inverse stable subordinator provides a probability model for time-fractional differential equations, and leads to explicit solution formulae. This paper reviews properties of the inverse stable subordinator, and applications to a variety of problems in mathematics and physics. Several different governing equations for the inverse stable subordinator have been proposed in the literature. This paper also shows how these equations can be reconciled. PMID:25045216
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.
LONG-TERM STABLE EQUILIBRIA FOR SYNCHRONOUS BINARY ASTEROIDS
Jacobson, Seth A.; Scheeres, Daniel J.
2011-07-20
Synchronous binary asteroids may exist in a long-term stable equilibrium, where the opposing torques from mutual body tides and the binary YORP (BYORP) effect cancel. Interior of this equilibrium, mutual body tides are stronger than the BYORP effect and the mutual orbit semimajor axis expands to the equilibrium; outside of the equilibrium, the BYORP effect dominates the evolution and the system semimajor axis will contract to the equilibrium. If the observed population of small (0.1-10 km diameter) synchronous binaries are in static configurations that are no longer evolving, then this would be confirmed by a null result in the observational tests for the BYORP effect. The confirmed existence of this equilibrium combined with a shape model of the secondary of the system enables the direct study of asteroid geophysics through the tidal theory. The observed synchronous asteroid population cannot exist in this equilibrium if described by the canonical 'monolithic' geophysical model. The 'rubble pile' geophysical model proposed by Goldreich and Sari is sufficient, however it predicts a tidal Love number directly proportional to the radius of the asteroid, while the best fit to the data predicts a tidal Love number inversely proportional to the radius. This deviation from the canonical and Goldreich and Sari models motivates future study of asteroid geophysics. Ongoing BYORP detection campaigns will determine whether these systems are in an equilibrium, and future determination of secondary shapes will allow direct determination of asteroid geophysical parameters.
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 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.
A belief-based evolutionarily stable strategy.
Deng, Xinyang; Wang, Zhen; Liu, Qi; Deng, Yong; Mahadevan, Sankaran
2014-11-21
As an equilibrium refinement of the Nash equilibrium, evolutionarily stable strategy (ESS) is a key concept in evolutionary game theory and has attracted growing interest. An ESS can be either a pure strategy or a mixed strategy. Even though the randomness is allowed in mixed strategy, the selection probability of pure strategy in a mixed strategy may fluctuate due to the impact of many factors. The fluctuation can lead to more uncertainty. In this paper, such uncertainty involved in mixed strategy has been further taken into consideration: a belief strategy is proposed in terms of Dempster-Shafer evidence theory. Furthermore, based on the proposed belief strategy, a belief-based ESS has been developed. The belief strategy and belief-based ESS can reduce to the mixed strategy and mixed ESS, which provide more realistic and powerful tools to describe interactions among agents.
Korshunov instantons out of equilibrium
NASA Astrophysics Data System (ADS)
Titov, M.; Gutman, D. B.
2016-04-01
Zero-dimensional dissipative action possesses nontrivial minima known as Korshunov instantons. They have been known so far only for imaginary time representation that is limited to equilibrium systems. In this work we reconstruct and generalise Korshunov instantons using real-time Keldysh approach. This allows us to formulate the dissipative action theory for generic nonequilibrium conditions. Possible applications of the theory to transport in strongly biased quantum dots are discussed.
Local equilibrium in bird flocks
NASA Astrophysics Data System (ADS)
Mora, Thierry; Walczak, Aleksandra M.; Del Castello, Lorenzo; Ginelli, Francesco; Melillo, Stefania; Parisi, Leonardo; Viale, Massimiliano; Cavagna, Andrea; Giardina, Irene
2016-12-01
The correlated motion of flocks is an example of global order emerging from local interactions. An essential difference with respect to analogous ferromagnetic systems is that flocks are active: animals move relative to each other, dynamically rearranging their interaction network. This non-equilibrium characteristic has been studied theoretically, but its impact on actual animal groups remains to be fully explored experimentally. Here, we introduce a novel dynamical inference technique, based on the principle of maximum entropy, which accommodates network rearrangements and overcomes the problem of slow experimental sampling rates. We use this method to infer the strength and range of alignment forces from data of starling flocks. We find that local bird alignment occurs on a much faster timescale than neighbour rearrangement. Accordingly, equilibrium inference, which assumes a fixed interaction network, gives results consistent with dynamical inference. We conclude that bird orientations are in a state of local quasi-equilibrium over the interaction length scale, providing firm ground for the applicability of statistical physics in certain active systems.
NASA Astrophysics Data System (ADS)
Ahmed, E.; El-Sayed, A. M. A.; El-Saka, H. A. A.
2007-01-01
In this paper we are concerned with the fractional-order predator-prey model and the fractional-order rabies model. Existence and uniqueness of solutions are proved. The stability of equilibrium points are studied. Numerical solutions of these models are given. An example is given where the equilibrium point is a centre for the integer order system but locally asymptotically stable for its fractional-order counterpart.
The stochastic link equilibrium strategy and algorithm for flow assignment in communication networks
NASA Astrophysics Data System (ADS)
Tao, Yang; Zhou, Xia
2005-11-01
Based on the mature user equilibrium (UE) theory in transportation field as well as the similarity of network flow between transportation and communication, in this paper, the user equilibrium theory was applied to communication networks, and how to apply the stochastic user equilibrium (SUE) to flow assigning in generalized communication networks was further studied. The stochastic link equilibrium (SLE) flow assignment strategy was proposed in this paper, the algorithm of SLE flow assignment was also provided. Both analyses and simulation based on the given algorithm proved that the optimal flow assignment in networks can be achieved by using this algorithm.
Symmetric and Asymmetric Tendencies in Stable Complex Systems
Tan, James P. L.
2016-01-01
A commonly used approach to study stability in a complex system is by analyzing the Jacobian matrix at an equilibrium point of a dynamical system. The equilibrium point is stable if all eigenvalues have negative real parts. Here, by obtaining eigenvalue bounds of the Jacobian, we show that stable complex systems will favor mutualistic and competitive relationships that are asymmetrical (non-reciprocative) and trophic relationships that are symmetrical (reciprocative). Additionally, we define a measure called the interdependence diversity that quantifies how distributed the dependencies are between the dynamical variables in the system. We find that increasing interdependence diversity has a destabilizing effect on the equilibrium point, and the effect is greater for trophic relationships than for mutualistic and competitive relationships. These predictions are consistent with empirical observations in ecology. More importantly, our findings suggest stabilization algorithms that can apply very generally to a variety of complex systems. PMID:27545722
Symmetric and Asymmetric Tendencies in Stable Complex Systems.
Tan, James P L
2016-08-22
A commonly used approach to study stability in a complex system is by analyzing the Jacobian matrix at an equilibrium point of a dynamical system. The equilibrium point is stable if all eigenvalues have negative real parts. Here, by obtaining eigenvalue bounds of the Jacobian, we show that stable complex systems will favor mutualistic and competitive relationships that are asymmetrical (non-reciprocative) and trophic relationships that are symmetrical (reciprocative). Additionally, we define a measure called the interdependence diversity that quantifies how distributed the dependencies are between the dynamical variables in the system. We find that increasing interdependence diversity has a destabilizing effect on the equilibrium point, and the effect is greater for trophic relationships than for mutualistic and competitive relationships. These predictions are consistent with empirical observations in ecology. More importantly, our findings suggest stabilization algorithms that can apply very generally to a variety of complex systems.
Approximate Equilibrium Shapes for Spinning, Gravitating Rubble Asteroids
NASA Astrophysics Data System (ADS)
Burns, Joseph A.; Sharma, I.; Jenkins, J. T.
2007-10-01
Approximate Equilibrium Shapes for Spinning, Gravitating Rubble Asteroids Joseph A. Burns, Ishan Sharma and James T. Jenkins Many asteroids are thought to be particle aggregates held together principally by self-gravity. Here we study those equilibrium shapes of spinning asteroids that are permitted for rubble piles. As in the case of spinning fluid masses, not all shapes may be compatible with a granular rheology. We take the asteroid to always be an ellipsoid with an interior modeled as a rigid-plastic, cohesion-less material. Using an approximate volume-averaged procedure, based on the classical method of moments, we investigate the dynamical process by which such objects may achieve equilibrium. First, to instill confidence in our approach, we have collapsed our dynamical approach to its statical limit to re-derive regions in spin-shape parameter space that allow equilibrium solutions to exist. Not surprisingly, our results duplicate static results reported by Holsapple (Icarus 154 [2001], 432; 172 [2004], 272) since the two sets of final equations match, although the formalisms to reach these expressions differ. We note that the approach applied here was obtained independently by I.S. in his Ph.D. dissertation (Cornell University, 2004); it provides a general, though approximate, framework that is amenable to systematic improvements and flexible enough to incorporate the dynamical effects of a changing shape, different rheologies and complex rotational histories. To demonstrate the power of our technique, we investigate the non-equilibrium dynamics of rigid-plastic, spinning, prolate asteroids to watch the simultaneous histories of shape and spin rate for rubble piles. We have succeeded in recovering most results of Richardson et al. (Icarus 173 [2004], 349), who obtained equilibrium shapes by studying numerically the passage into equilibrium of aggregates containing discrete, interacting, frictionless, spherical particles. Our mainly analytical approach aids
Adaptive Equilibrium Regulation: A Balancing Act in Two Timescales.
Boker, Steven M
2015-03-01
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.
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.
General equilibrium characteristics of a dual-lift helicopter system
NASA Technical Reports Server (NTRS)
Cicolani, L. S.; Kanning, G.
1986-01-01
The equilibrium characteristics of a dual-lift helicopter system are examined. The system consists of the cargo attached by cables to the endpoints of a spreader bar which is suspended by cables below two helicopters. Results are given for the orientation angles of the suspension system and its internal forces, and for the helicopter thrust vector requirements under general circumstances, including nonidentical helicopters, any accelerating or static equilibrium reference flight condition, any system heading relative to the flight direction, and any distribution of the load to the two helicopters. Optimum tether angles which minimize the sum of the required thrust magnitudes are also determined. The analysis does not consider the attitude degrees of freedom of the load and helicopters in detail, but assumes that these bodies are stable, and that their aerodynamic forces in equilibrium flight can be determined independently as functions of the reference trajectory. The ranges of these forces for sample helicopters and loads are examined and their effects on the equilibrium characteristics are given parametrically in the results.
Conformational stability of dimeric proteins: quantitative studies by equilibrium denaturation.
Neet, K. E.; Timm, D. E.
1994-01-01
The conformational stability of dimeric globular proteins can be measured by equilibrium denaturation studies in solvents such as guanidine hydrochloride or urea. Many dimeric proteins denature with a 2-state equilibrium transition, whereas others have stable intermediates in the process. For those proteins showing a single transition of native dimer to denatured monomer, the conformational stabilities, delta Gu (H2O), range from 10 to 27 kcal/mol, which is significantly greater than the conformational stability found for monomeric proteins. The relative contribution of quaternary interactions to the overall stability of the dimer can be estimated by comparing delta Gu (H2O) from equilibrium denaturation studies to the free energy associated with simple dissociation in the absence of denaturant. In many cases the large stabilization energy of dimers is primarily due to the intersubunit interactions and thus gives a rationale for the formation of oligomers. The magnitude of the conformational stability is related to the size of the polypeptide in the subunit and depends upon the type of structure in the subunit interface. The practical use, interpretation, and utility of estimation of conformational stability of dimers by equilibrium denaturation methods are discussed. PMID:7756976
Equilibrium and non-equilibrium metal-ceramic interfaces
Gao, Y.; Merkle, K.L.
1991-12-31
Metal-ceramic interfaces in thermodynamic equilibrium (Au/ZrO{sub 2}) and non-equilibrium (Au/MgO) have been studied by TEM and HREM. In the Au/ZrO{sub 2} system, ZrO{sub 2} precipitates formed by internal oxidation of a 7%Zr-Au alloy show a cubic ZrO{sub 2} phase. It appears that formation of the cubic ZrO{sub 2} is facilitated by alignment with the Au matrix. Most of the ZrO{sub 2} precipitates have a perfect cube-on-cube orientation relationship with the Au matrix. The large number of interfacial steps observed in a short-time annealing experiment indicate that the precipitates are formed by the ledge growth mechanism. The lowest interfacial energy is indicated by the dominance of closed-packed [111] Au/ZrO{sub 2} interfaces. In the Au/MgO system, composite films with small MgO smoke particles embedded in a Au matrix were prepared by a thin film technique. HREM observations show that most of the Au/MgO interfaces have a strong tendency to maintain a dense lattice structure across the interfaces irrespective of whether the interfaces are incoherent of semi-coherent. This indicates that there may be relatively strong bond between MgO and Au.
Equilibrium and non-equilibrium metal-ceramic interfaces
Gao, Y.; Merkle, K.L.
1991-01-01
Metal-ceramic interfaces in thermodynamic equilibrium (Au/ZrO{sub 2}) and non-equilibrium (Au/MgO) have been studied by TEM and HREM. In the Au/ZrO{sub 2} system, ZrO{sub 2} precipitates formed by internal oxidation of a 7%Zr-Au alloy show a cubic ZrO{sub 2} phase. It appears that formation of the cubic ZrO{sub 2} is facilitated by alignment with the Au matrix. Most of the ZrO{sub 2} precipitates have a perfect cube-on-cube orientation relationship with the Au matrix. The large number of interfacial steps observed in a short-time annealing experiment indicate that the precipitates are formed by the ledge growth mechanism. The lowest interfacial energy is indicated by the dominance of closed-packed (111) Au/ZrO{sub 2} interfaces. In the Au/MgO system, composite films with small MgO smoke particles embedded in a Au matrix were prepared by a thin film technique. HREM observations show that most of the Au/MgO interfaces have a strong tendency to maintain a dense lattice structure across the interfaces irrespective of whether the interfaces are incoherent of semi-coherent. This indicates that there may be relatively strong bond between MgO and Au.
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.
EQUILIBRIUM ROTATION OF SEMILIQUID EXOPLANETS AND SATELLITES
Makarov, Valeri V.
2015-09-01
A wide range of exoplanet and exomoon models are characterized by a finite average rigidity and a viscosity much lower than the typical values for terrestrials. Such semiliquid bodies may or may not have rigid crusts with permanent figures. Unlike planets with solid mantles and Earth-like rheology, semiliquid bodies can be captured into stable pseudosynchronous spin resonance, where the average rate of rotation is higher than the synchronous 1:1 resonance. Two basic conditions are derived for capture of planets with a triaxial figure into pseudosynchronous rotation, one related to the characteristic tidal wave number (the product of the tidal frequency by the Maxwell time), and the other to the orbital eccentricity. If a semiliquid object does not satisfy either of the two conditions, it is captured into the synchronous resonance. For nearly axially symmetric bodies, only the first condition is in place, and the other is much relaxed, so they should predominantly be pseudosynchronous. It is also pointed out that the equilibrium pseudosychronous rotation rate can not reach the widely used asymptotic value from the constant time lag model but is in reality closer to the synchronous spin.
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.
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.
Equilibrium and stability code for a diffuse plasma
Betancourt, Octavio; Garabedian, Paul
1976-01-01
A computer code to investigate the equilibrium and stability of a diffuse plasma in three dimensions is described that generalizes earlier work on a sharp free boundary model. Toroidal equilibria of a plasma are determined by considering paths of steepest descent associated with a new version of the variational principle of magnetohydrodynamics that involves mapping a fixed coordinate domain onto the plasma. A discrete approximation of the potential energy is written down following the finite element method, and the resulting expression is minimized with respect to the values of the mapping at points of a rectangular grid. If a relative minimum of the discrete analogue of the energy is attained, the corresponding equilibrium is considered to be stable. PMID:16592310
[Hardy-Weinberg equilibrium in genetic epidemiology].
Liu, Hong; Hu, Yonghua
2010-01-01
Hardy-Weinberg equilibrium test is the base of genetic epidemiology. The new methods for Hardy-Weinberg equilibrium test involve: X chromosome-linked single nucleotide polymorphism Hardy-Weinberg test, inbreeding coefficient (F) test, an incomplete enumeration algorithm for an exact test of Hardy-Weinberg proportions with multiple alleles, and graphical tests for Hardy-Weinberg equilibrium based on the ternary plot. It is necessary to conduct Hardy-Weinberg equilibrium test in genetic epidemiology studies and adjust the associations as deviation of Hardy-Weinberg equilibrium occurs.
The geometry of structural equilibrium
2017-01-01
Building on a long tradition from Maxwell, Rankine, Klein and others, this paper puts forward a geometrical description of structural equilibrium which contains a procedure for the graphic analysis of stress resultants within general three-dimensional frames. The method is a natural generalization of Rankine’s reciprocal diagrams for three-dimensional trusses. The vertices and edges of dual abstract 4-polytopes are embedded within dual four-dimensional vector spaces, wherein the oriented area of generalized polygons give all six components (axial and shear forces with torsion and bending moments) of the stress resultants. The relevant quantities may be readily calculated using four-dimensional Clifford algebra. As well as giving access to frame analysis and design, the description resolves a number of long-standing problems with the incompleteness of Rankine’s description of three-dimensional trusses. Examples are given of how the procedure may be applied to structures of engineering interest, including an outline of a two-stage procedure for addressing the equilibrium of loaded gridshell rooves.
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…
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…
Instability versus equilibrium propagation of a laser beam in plasma.
Lushnikov, Pavel M; Rose, Harvey A
2004-06-25
We obtain, for the first time, an analytic theory of the forward stimulated Brillouin scattering instability of a spatially and temporally incoherent laser beam that controls the transition between statistical equilibrium and nonequilibrium (unstable) self-focusing regimes of beam propagation. The stability boundary may be used as a comprehensive guide for inertial confinement fusion designs. Well into the stable regime, an analytic expression for the angular diffusion coefficient is obtained, which provides an essential correction to a geometric optic approximation for beam propagation.
Efficient Methods for Stable Distributions
2007-11-02
are used, corresponding to the common values used in digital signal processing. Five new functions for discrete/quantized stable distributions were...written. • sgendiscrete generates discrete stable random variates. It works by generating continuous stable random variables using the Chambers- Mallows ...with stable distributions. It allows engineers and scientists to analyze data and work with stable distributions within the common matlab environment
Nanomechanics Model for Static Equilibrium
NASA Astrophysics Data System (ADS)
Jung, Sunghoon
2002-09-01
This study presented a computational technique to model and simulate atomistic behavior of materials under static loads, Interatomic potential energy was used to maintain equilibrium among atoms under static loads and constraints, In addition, the atomistic model was coupled with the finite element analysis model so that more flexible loads and constraints could be applied to the atomistic model A multi-scale technique was also presented for some single wall nanotubes of both zigzag and armchair and then their effective stiffness were estimated Those designed nanotubes are woven into fabric composites, which can be used in various military applications including body armored, vehicles, and infantry transportation vehicles because advanced nano- composites could be much lighter and stronger than current ones, Some example problems were presented to illustrate the developed technique for the nano-composites and SWNTs, The proposed technique for nanomechanics can be used for design and analysis of materials at the atomic or molecular level,
Equilibrium structure of ferrofluid aggregates.
Yoon, Mina; Tománek, David
2010-11-17
We study the equilibrium structure of large but finite aggregates of magnetic dipoles, representing a colloidal suspension of magnetite particles in a ferrofluid. With increasing system size, the structural motif evolves from chains and rings to multi-chain and multi-ring assemblies. Very large systems form single- and multi-wall coils, tubes and scrolls. These structural changes result from a competition between various energy terms, which can be approximated analytically within a continuum model. We also study the effect of external parameters such as magnetic field on the relative stability of these structures. Our results may give insight into experimental data obtained during solidification of ferrofluid aggregates at temperatures where thermal fluctuations become negligible in comparison to inter-particle interactions. These data may also help to experimentally control the aggregation of magnetic particles.
Equilibrium structure of ferrofluid aggregates
Yoon, Mina; Tomanek, David
2010-01-01
We study the equilibrium structure of large but finite aggregates of magnetic dipoles, representing a colloidal suspension of magnetite particles in a ferrofluid. With increasing system size, the structural motif evolves from chains and rings to multi-chain and multi-ring assemblies. Very large systems form single- and multi-wall coils, tubes and scrolls. These structural changes result from a competition between various energy terms, which can be approximated analytically within a continuum model. We also study the effect of external parameters such as magnetic field on the relative stability of these structures. Our results may give insight into experimental data obtained during solidification of ferrofluid aggregates at temperatures where thermal fluctuations become negligible in comparison to inter-particle interactions. These data may also help to experimentally control the aggregation of magnetic particles.
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 avalanches in spin glasses
NASA Astrophysics Data System (ADS)
Le Doussal, Pierre; Müller, Markus; Wiese, Kay Jörg
2012-06-01
We study the distribution of equilibrium avalanches (shocks) in Ising spin glasses which occur at zero temperature upon small changes in the magnetic field. For the infinite-range Sherrington-Kirkpatrick (SK) model, we present a detailed derivation of the density ρ(ΔM) of the magnetization jumps ΔM. It is obtained by introducing a multicomponent generalization of the Parisi-Duplantier equation, which allows us to compute all cumulants of the magnetization. We find that ρ(ΔM)˜ΔM-τ with an avalanche exponent τ=1 for the SK model, originating from the marginal stability (criticality) of the model. It holds for jumps of size 1≪ΔM
Revised lattice Boltzmann model for traffic flow with equilibrium traffic pressure
NASA Astrophysics Data System (ADS)
Shi, Wei; Lu, Wei-Zhen; Xue, Yu; He, Hong-Di
2016-02-01
A revised lattice Boltzmann model concerning the equilibrium traffic pressure is proposed in this study to tackle the phase transition phenomena of traffic flow system. The traditional lattice Boltzmann model has limitation to investigate the complex traffic phase transitions due to its difficulty for modeling the equilibrium velocity distribution. Concerning this drawback, the equilibrium traffic pressure is taken into account to derive the equilibrium velocity distribution in the revised lattice Boltzmann model. In the proposed model, a three-dimensional velocity-space is assumed to determine the equilibrium velocity distribution functions and an alternative, new derivative approach is introduced to deduct the macroscopic equations with the first-order accuracy level from the lattice Boltzmann model. Based on the linear stability theory, the stability conditions of the corresponding macroscopic equations can be obtained. The outputs indicate that the stability curve is divided into three regions, i.e., the stable region, the neutral stability region, and the unstable region. In the stable region, small disturbance appears in the initial uniform flow and will vanish after long term evolution, while in the unstable region, the disturbance will be enlarged and finally leads to the traffic system entering the congested state. In the neutral stability region, small disturbance does not vanish with time and maintains its amplitude in the traffic system. Conclusively, the stability of traffic system is found to be enhanced as the equilibrium traffic pressure increases. Finally, the numerical outputs of the proposed model are found to be consistent with the recognized, theoretical results.
ERIC Educational Resources Information Center
Greenwell, Raymond N.; Seabold, Daniel E.
2014-01-01
The Gale-Shapley stable marriage theorem is a fascinating piece of twentieth-century mathematics that has many practical applications--from labor markets to school admissions--yet is accessible to secondary school mathematics students. David Gale and Lloyd Shapley were both mathematicians and economists who published their work on the Stable…
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.
Computer simulation of the toroidal equilibrium and stability of a plasma in three dimensions.
Betancourt, O; Garabedian, P
1975-03-01
A computer program has been written to solve the equations for sharp boundary magnetohydrodynamic equilibrium of a toroidal plasma in three dimensions without restriction to axial symmetry. The numerical method is based on a variational principle that indicates whether the equilibria obtained are stable. Applications have been made to Tokamak, Stellarator, and Scyllac configurations.
Computer Simulation of the Toroidal Equilibrium and Stability of a Plasma in Three Dimensions
Betancourt, Octavio; Garabedian, Paul
1975-01-01
A computer program has been written to solve the equations for sharp boundary magnetohydrodynamic equilibrium of a toroidal plasma in three dimensions without restriction to axial symmetry. The numerical method is based on a variational principle that indicates whether the equilibria obtained are stable. Applications have been made to Tokamak, Stellarator, and Scyllac configurations. PMID:16592233
ERIC Educational Resources Information Center
Privat, Romain; Jaubert, Jean-Noe¨l; Berger, Etienne; Coniglio, Lucie; Lemaitre, Ce´cile; Meimaroglou, Dimitrios; Warth, Vale´rie
2016-01-01
Robust and fast methods for chemical or multiphase equilibrium calculation are routinely needed by chemical-process engineers working on sizing or simulation aspects. Yet, while industrial applications essentially require calculation tools capable of discriminating between stable and nonstable states and converging to nontrivial solutions,…
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 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.
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 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.
Statistical equilibrium predictions of jets and spots on Jupiter
Turkington, Bruce; Majda, Andrew; Haven, Kyle; DiBattista, Mark
2001-01-01
An equilibrium statistical theory of coherent structures is applied to midlatitude bands in the northern and southern hemispheres of Jupiter. The theory imposes energy and circulation constraints on the large-scale motion and uses a prior distribution on potential vorticity fluctuations to parameterize the small-scale turbulent eddies. Nonlinearly stable coherent structures are computed by solving the constrained maximum entropy principle governing the equilibrium states of the statistical theory. The theoretical predictions are consistent with the observed large-scale features of the weather layer if and only if the prior distribution has anticyclonic skewness, meaning that intense anticyclones predominate at small scales. Then the computations show that anticyclonic vortices emerge at the latitudes of the Great Red Spot and the White Ovals in the southern band, whereas in the northern band no vortices form within the zonal jets. Recent observational data from the Galileo mission support the occurrence of intense small-scale anticyclonic forcing. The results suggest the possibility of using equilibrium statistical theory for inverse modeling of the small-scale characteristics of the Jovian atmosphere from observed features. PMID:11592986
Equilibrium coexistence of three amphiboles
Robinson, P.; Jaffe, H.W.; Klein, C.; 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
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
On out of plane equilibrium points in photo-gravitational restricted three-body problem
NASA Astrophysics Data System (ADS)
Das, M. K.; Narang, Pankaj; Mahajan, S.; Yuasa, M.
2009-12-01
We have investigated the out of plane equilibrium points of a passive micron size particle and their stability in the field of radiating binary stellar systems Krüger-60, RW-Monocerotis within the framework of photo-gravitational circular restricted three-body problem. We find that the out of plane equilibrium points ( L i , i = 6, 7, 8, 9) may exist for range of β 1 (ratio of radiation to gravitational force of the massive component) values for these binary systems in the presence of Poynting-Robertson drag (hereafter PR-drag). In the absence of PR-drag, we find that the motion of a particle near the equilibrium points L 6,7 is stable in both the binary systems for a specific range of β 1 values. The PR-drag is shown to cause instability of the various out of plane equilibrium points in these binary systems.
RINGED ACCRETION DISKS: EQUILIBRIUM CONFIGURATIONS
Pugliese, D.; Stuchlík, Z. E-mail: zdenek.stuchlik@physics.cz
2015-12-15
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.
Stable glow discharge detector
Koo, Jackson C.; Yu, Conrad M.
2004-05-18
A highly sensitive electronic ion cell for the measurement of trace elements in He carrier gas which involves glow discharge. A constant wave (CW) stable glow discharge detector which is controlled through a biased resistor, can detect the change of electron density caused by impurities in the He carrier gas by many orders of magnitude larger than that caused by direct ionization or electron capture. The stable glow discharge detector utilizes a floating pseudo-electrode to form a probe in or near the plasma and a solid rod electrode. By using this probe, the large variation of electron density due to trace amounts of impurities can be directly measured. The solid rod electrode provides greater stability and thus easier alignment.
O'Neil, J.R.
1977-01-01
Stable isotope fractionations between minerals are functions of the fundamental vibrational frequencies of the minerals and therefore bear on several topics of mineralogical interest. Isotopic compositions of the elements H, C, O, Si, and S can now be determined routinely in almost any mineral. A summary has been made of both published and new results of laboratory investigations, analyses of natural materials, and theoretical considerations which bear on the importance of temperature, pressure, chemical composition and crystal structure to the isotopic properties of minerals. It is shown that stable isotope studies can sometimes provide evidence for elucidating details of crystal structure and can be a powerful tool for use in tracing the reaction paths of mineralogical reactions. ?? 1977 Springer-Verlag.
Stable local oscillator module.
Brocato, Robert Wesley
2007-11-01
This report gives a description of the development of a Stable Local Oscillator (StaLO) multi-chip module (MCM). It is a follow-on report to SAND2006-6414, Stable Local Oscillator Microcircuit. The StaLO accepts a 100MHz input signal and produces output signals at 1.2, 3.3, and 3.6 GHz. The circuit is built as a multi-chip module (MCM), since it makes use of integrated circuit technologies in silicon and lithium niobate as well as discrete passive components. This report describes the development of an MCM-based version of the complete StaLO, fabricated on an alumina thick film hybrid substrate.
Skoryna, S.C.
1981-01-01
This book presents information on the following topics: chemistry of strontium; biogeochemistry of strontium; uptake of stable strontium by plants and effects on plant growth; divalent cation-dependent deposits in paramecium; effects of strontium ion on the hydrolysis of ATP; stronium ions and membranes - screening versus binding at charged surfaces; mitochondrial granules in the liver of rats kept on stable strontium supplementation; divalent cations and regulation of cyclic nucleotides in nervous systems; strontium as the substitute for calcium in the excitation-contraction coupling of crayfish muscle fibers; hemodynamic effects of strontium in the dog; some mechanical characteristics of strontium-mediated contractions in heart muscle; effects of calcium, magnesium, and strontium on drug-receptor interactions; strontium and histamine secretion; and effects of strontium in human dental enamel.
Thermally stable laminating resins
NASA Technical Reports Server (NTRS)
Jones, R. J.; Vaughan, R. W.; Burns, E. A.
1972-01-01
Improved thermally stable laminating resins were developed based on the addition-type pyrolytic polymerization. Detailed monomer and polymer synthesis and characterization studies identified formulations which facilitate press molding processing and autoclave fabrication of glass and graphite fiber reinforced composites. A specific resin formulation, termed P10P was utilized to prepare a Courtaulds HMS reinforced simulated airfoil demonstration part by an autoclave molding process.
Forensic Stable Isotope Biogeochemistry
NASA Astrophysics Data System (ADS)
Cerling, Thure E.; Barnette, Janet E.; Bowen, Gabriel J.; Chesson, Lesley A.; Ehleringer, James R.; Remien, Christopher H.; Shea, Patrick; Tipple, Brett J.; West, Jason B.
2016-06-01
Stable isotopes are being used for forensic science studies, with applications to both natural and manufactured products. In this review we discuss how scientific evidence can be used in the legal context and where the scientific progress of hypothesis revisions can be in tension with the legal expectations of widely used methods for measurements. Although this review is written in the context of US law, many of the considerations of scientific reproducibility and acceptance of relevant scientific data span other legal systems that might apply different legal principles and therefore reach different conclusions. Stable isotopes are used in legal situations for comparing samples for authenticity or evidentiary considerations, in understanding trade patterns of illegal materials, and in understanding the origins of unknown decedents. Isotope evidence is particularly useful when considered in the broad framework of physiochemical processes and in recognizing regional to global patterns found in many materials, including foods and food products, drugs, and humans. Stable isotopes considered in the larger spatial context add an important dimension to forensic science.
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.}
Detonation of Meta-stable Clusters
Kuhl, Allen; Kuhl, Allen L.; Fried, Laurence E.; Howard, W. Michael; Seizew, Michael R.; Bell, John B.; Beckner, Vincent; Grcar, Joseph F.
2008-05-31
We consider the energy accumulation in meta-stable clusters. This energy can be much larger than the typical chemical bond energy (~;;1 ev/atom). For example, polymeric nitrogen can accumulate 4 ev/atom in the N8 (fcc) structure, while helium can accumulate 9 ev/atom in the excited triplet state He2* . They release their energy by cluster fission: N8 -> 4N2 and He2* -> 2He. We study the locus of states in thermodynamic state space for the detonation of such meta-stable clusters. In particular, the equilibrium isentrope, starting at the Chapman-Jouguet state, and expanding down to 1 atmosphere was calculated with the Cheetah code. Large detonation pressures (3 and 16 Mbar), temperatures (12 and 34 kilo-K) and velocities (20 and 43 km/s) are a consequence of the large heats of detonation (6.6 and 50 kilo-cal/g) for nitrogen and helium clusters respectively. If such meta-stable clusters could be synthesized, they offer the potential for large increases in the energy density of materials.
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.
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.
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…
Far from Equilibrium: The Gas Pendulum.
ERIC Educational Resources Information Center
Soltzberg, Leonard J.
1986-01-01
Discusses the importance of studying the far-from-equilibrium phenomena in college chemistry. Presents a system using the gas pendulum which displays all of the essential characteristics of dissipative systems. Promotes the use of the gas pendulum as a teaching example of a nonlinear far-from-equilibrium process. (TW)
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.
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…
Information-theoretic equilibrium and observable thermalization
Anzà, F.; Vedral, V.
2017-01-01
A crucial point in statistical mechanics is the definition of the notion of thermal equilibrium, which can be given as the state that maximises the von Neumann entropy, under the validity of some constraints. Arguing that such a notion can never be experimentally probed, in this paper we propose a new notion of thermal equilibrium, focused on observables rather than on the full state of the quantum system. We characterise such notion of thermal equilibrium for an arbitrary observable via the maximisation of its Shannon entropy and we bring to light the thermal properties that it heralds. The relation with Gibbs ensembles is studied and understood. We apply such a notion of equilibrium to a closed quantum system and show that there is always a class of observables which exhibits thermal equilibrium properties and we give a recipe to explicitly construct them. Eventually, an intimate connection with the Eigenstate Thermalisation Hypothesis is brought to light. PMID:28266646
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.
Information-theoretic equilibrium and observable thermalization
NASA Astrophysics Data System (ADS)
Anzà, F.; Vedral, V.
2017-03-01
A crucial point in statistical mechanics is the definition of the notion of thermal equilibrium, which can be given as the state that maximises the von Neumann entropy, under the validity of some constraints. Arguing that such a notion can never be experimentally probed, in this paper we propose a new notion of thermal equilibrium, focused on observables rather than on the full state of the quantum system. We characterise such notion of thermal equilibrium for an arbitrary observable via the maximisation of its Shannon entropy and we bring to light the thermal properties that it heralds. The relation with Gibbs ensembles is studied and understood. We apply such a notion of equilibrium to a closed quantum system and show that there is always a class of observables which exhibits thermal equilibrium properties and we give a recipe to explicitly construct them. Eventually, an intimate connection with the Eigenstate Thermalisation Hypothesis is brought to light.
Information-theoretic equilibrium and observable thermalization.
Anzà, F; Vedral, V
2017-03-07
A crucial point in statistical mechanics is the definition of the notion of thermal equilibrium, which can be given as the state that maximises the von Neumann entropy, under the validity of some constraints. Arguing that such a notion can never be experimentally probed, in this paper we propose a new notion of thermal equilibrium, focused on observables rather than on the full state of the quantum system. We characterise such notion of thermal equilibrium for an arbitrary observable via the maximisation of its Shannon entropy and we bring to light the thermal properties that it heralds. The relation with Gibbs ensembles is studied and understood. We apply such a notion of equilibrium to a closed quantum system and show that there is always a class of observables which exhibits thermal equilibrium properties and we give a recipe to explicitly construct them. Eventually, an intimate connection with the Eigenstate Thermalisation Hypothesis is brought to light.
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.
How Far from Equilibrium Is Active Matter?
Fodor, Étienne; Nardini, Cesare; Cates, Michael E; Tailleur, Julien; Visco, Paolo; van Wijland, Frédéric
2016-07-15
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.
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.
Dienemann, Jacqueline
2002-01-01
This article examines one outcome of leadership: productive achievement. Without achievement one is judged to not truly be a leader. Thus, the ideal leader must be a visionary, a critical thinker, an expert, a communicator, a mentor, and an achiever of organizational goals. This article explores the organizational context that supports achievement, measures of quality nursing care, fiscal accountability, leadership development, rewards and punishments, and the educational content and teaching strategies to prepare graduates to be achievers.
Caulkins, Jonathan P; Feichtinger, Gustav; Grass, Dieter; Hartl, Richard F; Kort, Peter M; Novak, Andreas J; Seidl, Andrea
2013-03-16
We present a novel model of corruption dynamics in the form of a nonlinear optimal dynamic control problem. It has a tipping point, but one whose origins and character are distinct from that in the classic Schelling (1978) model. The decision maker choosing a level of corruption is the chief or some other kind of authority figure who presides over a bureaucracy whose state of corruption is influenced by the authority figure's actions, and whose state in turn influences the pay-off for the authority figure. The policy interpretation is somewhat more optimistic than in other tipping models, and there are some surprising implications, notably that reforming the bureaucracy may be of limited value if the bureaucracy takes its cues from a corrupt leader.
NASA Astrophysics Data System (ADS)
Guo, Jing; Qu, Hong-wei; Liu, Li-gang; Sun, Yan-liang; Zhang, Yue; Yang, Qing-xiang
2013-02-01
A high speed steel (HSS) was studied for rollers in this work. The steel was quenched at 1150°C and tempered at 520°C. The phase structures of the steel were determined by X-ray diffraction (XRD), and the hardness of specimens was measured. The volume fraction of carbides was counted by Image-Pro Plus software. The typical microstructures were observed by field emission scanning electron microscope (FESEM). Stable and meta-stable carbides were deduced by removing the existing phases one by one in the Fe-C equilibrium calculation. It is found that the precipitated carbides are bulk-like MC, long stripe-like M2C, fishbone-like M6C, and daisy-like M7C3 during the tempering process. The stable carbides are MC and M6C, but the meta-stable ones are M2C, M7C3, and M3C.
Dotov, D G; Kim, S; Frank, T D
2015-02-01
We derive explicit expressions for the non-equilibrium thermodynamical variables of a canonical-dissipative limit cycle oscillator describing rhythmic motion patterns of active systems. These variables are statistical entropy, non-equilibrium internal energy, and non-equilibrium free energy. In particular, the expression for the non-equilibrium free energy is derived as a function of a suitable control parameter. The control parameter determines the Hopf bifurcation point of the deterministic active system and describes the effective pumping of the oscillator. In analogy to the equilibrium free energy of the Landau theory, it is shown that the non-equilibrium free energy decays as a function of the control parameter. In doing so, a similarity between certain equilibrium and non-equilibrium phase transitions is pointed out. Data from an experiment on human rhythmic movements is presented. Estimates for pumping intensity as well as the thermodynamical variables are reported. It is shown that in the experiment the non-equilibrium free energy decayed when pumping intensity was increased, which is consistent with the theory. Moreover, pumping intensities close to zero could be observed at relatively slow intended rhythmic movements. In view of the Hopf bifurcation underlying the limit cycle oscillator model, this observation suggests that the intended limit cycle movements were actually more similar to trajectories of a randomly perturbed stable focus.
Marginally Stable Nuclear Burning
NASA Technical Reports Server (NTRS)
Strohmayer, Tod E.; Altamirano, D.
2012-01-01
Thermonuclear X-ray bursts result from unstable nuclear burning of the material accreted on neutron stars in some low mass X-ray binaries (LMXBs). Theory predicts that close to the boundary of stability oscillatory burning can occur. This marginally stable regime has so far been identified in only a small number of sources. We present Rossi X-ray Timing Explorer (RXTE) observations of the bursting, high- inclination LMXB 4U 1323-619 that reveal for the first time in this source the signature of marginally stable burning. The source was observed during two successive RXTE orbits for approximately 5 ksec beginning at 10:14:01 UTC on March 28, 2011. Significant mHz quasi- periodic oscillations (QPO) at a frequency of 8.1 mHz are detected for approximately 1600 s from the beginning of the observation until the occurrence of a thermonuclear X-ray burst at 10:42:22 UTC. The mHz oscillations are not detected following the X-ray burst. The average fractional rms amplitude of the mHz QPOs is 6.4% (3 - 20 keV), and the amplitude increases to about 8% below 10 keV.This phenomenology is strikingly similar to that seen in the LMXB 4U 1636-53. Indeed, the frequency of the mHz QPOs in 4U 1323-619 prior to the X-ray burst is very similar to the transition frequency between mHz QPO and bursts found in 4U 1636-53 by Altamirano et al. (2008). These results strongly suggest that the observed QPOs in 4U 1323-619 are, like those in 4U 1636-53, due to marginally stable nuclear burning. We also explore the dependence of the energy spectrum on the oscillation phase, and we place the present observations within the context of the spectral evolution of the accretion-powered flux from the source.
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.…
ERIC Educational Resources Information Center
Anderson, Sharon; Medrich, Elliott; Fowler, Donna
2007-01-01
From the halls of Congress to the local elementary school, conversations on education reform have tossed around the term "achievement gap" as though people all know precisely what that means. As it's commonly used, "achievement gap" refers to the differences in scores on state or national achievement tests between various…
Stable local oscillator microcircuit.
Brocato, Robert Wesley
2006-10-01
This report gives a description of the development of a Stable Local Oscillator (StaLO) Microcircuit. The StaLO accepts a 100MHz input signal and produces output signals at 1.2, 3.3, and 3.6 GHz. The circuit is built as a multi-chip module (MCM), since it makes use of integrated circuit technologies in silicon and lithium niobate as well as discrete passive components. The StaLO uses a comb generator followed by surface acoustic wave (SAW) filters. The comb generator creates a set of harmonic components of the 100MHz input signal. The SAW filters are narrow bandpass filters that are used to select the desired component and reject all others. The resulting circuit has very low sideband power levels and low phase noise (both less than -40dBc) that is limited primarily by the phase noise level of the input signal.
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…
Stable umbral chromospheric structures
NASA Astrophysics Data System (ADS)
Henriques, V. M. J.; Scullion, E.; Mathioudakis, M.; Kiselman, D.; Gallagher, P. T.; Keenan, F. P.
2015-02-01
Aims: We seek to understand the morphology of the chromosphere in sunspot umbra. We investigate if the horizontal structures observed in the spectral core of the Ca II H line are ephemeral visuals caused by the shock dynamics of more stable structures, and examine their relationship with observables in the H-alpha line. Methods: Filtergrams in the core of the Ca II H and H-alpha lines as observed with the Swedish 1-m Solar Telescope are employed. We utilise a technique that creates composite images and tracks the flash propagation horizontally. Results: We find 0.̋15 wide horizontal structures, in all of the three target sunspots, for every flash where the seeing is moderate to good. Discrete dark structures are identified that are stable for at least two umbral flashes, as well as systems of structures that live for up to 24 min. We find cases of extremely extended structures with similar stability, with one such structure showing an extent of 5''. Some of these structures have a correspondence in H-alpha, but we were unable to find a one-to-one correspondence for every occurrence. If the dark streaks are formed at the same heights as umbral flashes, there are systems of structures with strong departures from the vertical for all three analysed sunspots. Conclusions: Long-lived Ca II H filamentary horizontal structures are a common and likely ever-present feature in the umbra of sunspots. If the magnetic field in the chromosphere of the umbra is indeed aligned with the structures, then the present theoretical understanding of the typical umbra needs to be revisited. Movies associated to Figs. 3 and 4 are available in electronic form at http://www.aanda.org
Real Time Computation of Kinetic Constraints to Support Equilibrium Reconstruction
NASA Astrophysics Data System (ADS)
Eggert, W. J.; Kolemen, E.; Eldon, D.
2016-10-01
A new method for quickly and automatically applying kinetic constraints to EFIT equilibrium reconstructions using readily available data is presented. The ultimate goal is to produce kinetic equilibrium reconstructions in real time and use them to constrain the DCON stability code as part of a disruption avoidance scheme. A first effort presented here replaces CPU-time expensive modules, such as the fast ion pressure profile calculation, with a simplified model. We show with a DIII-D database analysis that we can achieve reasonable predictions for selected applications by modeling the fast ion pressure profile and determining the fit parameters as functions of easily measured quantities including neutron rate and electron temperature on axis. Secondly, we present a strategy for treating Thomson scattering and Charge Exchange Recombination data to automatically form constraints for a kinetic equilibrium reconstruction, a process that historically was performed by hand. Work supported by US DOE DE-AC02-09CH11466 and DE-FC02-04ER54698.
Holdener, Fred R.; Boyd, Robert D.
2000-01-01
The present invention is a bi-stable optical actuator device that is depowered in both stable positions. A bearing is used to transfer motion and smoothly transition from one state to another. The optical actuator device may be maintained in a stable position either by gravity or a restraining device.
Economic Impact of Stable Flies
Technology Transfer Automated Retrieval System (TEKTRAN)
A dynamic model was created to estimate the economic impact of stable flies on livestock production. Based upon a nationwide average of 10 stable flies per animal for 3 months per year, the model estimates the impact of stable flies to be $543 million to the dairy industry, $1.34 billion to pasture ...
Rapid Equilibrium-Ordered Enzyme Mechanisms.
ERIC Educational Resources Information Center
Chauncey, Thomas R.; And Others
1985-01-01
Discusses: (1) characteristic initial velocity behavior (considering the five-step reaction sequence for rapid equilibrium-order bisubstrate mechanisms); (2) dead-end inhibition; (3) inhibition by single products; and (4) an activator as a leading reactant. (JN)
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.
Equilibrium capillary forces with atomic force microscopy.
Sprakel, J; Besseling, N A M; Leermakers, F A M; Cohen Stuart, M A
2007-09-07
We present measurements of equilibrium forces resulting from capillary condensation. The results give access to the ultralow interfacial tensions between the capillary bridge and the coexisting bulk phase. We demonstrate this with solutions of associative polymers and an aqueous mixture of gelatin and dextran, with interfacial tensions around 10 microN/m. The equilibrium nature of the capillary forces is attributed to the combination of a low interfacial tension and a microscopic confinement geometry, based on nucleation and growth arguments.
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
Approaches to the Treatment of Equilibrium Perturbations
NASA Astrophysics Data System (ADS)
Canagaratna, Sebastian G.
2003-10-01
Perturbations from equilibrium are treated in the textbooks by a combination of Le Châtelier's principle, the comparison of the equilibrium constant K with the reaction quotient Q,and the kinetic approach. Each of these methods is briefly reviewed. This is followed by derivations of the variation of the equilibrium value of the extent of reaction, ξeq, with various parameters on which it depends. Near equilibrium this relationship can be represented by a straight line. The equilibrium system can be regarded as moving on this line as the parameter is varied. The slope of the line depends on quantities like enthalpy of reaction, volume of reaction and so forth. The derivation shows that these quantities pertain to the equilibrium system, not the standard state. Also, the derivation makes clear what kind of assumptions underlie our conclusions. The derivation of these relations involves knowledge of thermodynamics that is well within the grasp of junior level physical chemistry students. The conclusions that follow from the derived relations are given as subsidiary rules in the form of the slope of ξeq, with T, p, et cetera. The rules are used to develop a visual way of predicting the direction of shift of a perturbed system. This method can be used to supplement one of the other methods even at the introductory level.
Mai, Huajun; Shiraiwa, Manabu; Flagan, Richard C; Seinfeld, John H
2015-10-06
The prevailing treatment of secondary organic aerosol formation in atmospheric models is based on the assumption of instantaneous gas-particle equilibrium for the condensing species, yet compelling experimental evidence indicates that organic aerosols can exhibit the properties of highly viscous, semisolid particles, for which gas-particle equilibrium may be achieved slowly. The approach to gas-particle equilibrium partitioning is controlled by gas-phase diffusion, interfacial transport, and particle-phase diffusion. Here we evaluate the controlling processes and the time scale to achieve gas-particle equilibrium as a function of the volatility of the condensing species, its surface accommodation coefficient, and its particle-phase diffusivity. For particles in the size range of typical atmospheric organic aerosols (∼50-500 nm), the time scale to establish gas-particle equilibrium is generally governed either by interfacial accommodation or particle-phase diffusion. The rate of approach to equilibrium varies, depending on whether the bulk vapor concentration is constant, typical of an open system, or decreasing as a result of condensation into the particles, typical of a closed system.
Dynamic clonal equilibrium and predetermined cancer risk in Barrett's oesophagus
Martinez, Pierre; Timmer, Margriet R.; Lau, Chiu T.; Calpe, Silvia; Sancho-Serra, Maria del Carmen; Straub, Danielle; Baker, Ann-Marie; Meijer, Sybren L.; Kate, Fiebo J. W. ten; Mallant-Hent, Rosalie C.; Naber, Anton H. J.; van Oijen, Arnoud H. A. M.; Baak, Lubbertus C.; Scholten, Pieter; Böhmer, Clarisse J. M.; Fockens, Paul; Bergman, Jacques J. G. H. M.; Maley, Carlo C.; Graham, Trevor A.; Krishnadath, Kausilia K
2016-01-01
Surveillance of Barrett's oesophagus allows us to study the evolutionary dynamics of a human neoplasm over time. Here we use multicolour fluorescence in situ hybridization on brush cytology specimens, from two time points with a median interval of 37 months in 195 non-dysplastic Barrett's patients, and a third time point in a subset of 90 patients at a median interval of 36 months, to study clonal evolution at single-cell resolution. Baseline genetic diversity predicts progression and remains in a stable dynamic equilibrium over time. Clonal expansions are rare, being detected once every 36.8 patient years, and growing at an average rate of 1.58 cm2 (95% CI: 0.09–4.06) per year, often involving the p16 locus. This suggests a lack of strong clonal selection in Barrett's and that the malignant potential of ‘benign' Barrett's lesions is predetermined, with important implications for surveillance programs. PMID:27538785
Emission properties of non-equilibrium krypton plasma in the water-window region
NASA Astrophysics Data System (ADS)
Zakharov, Vassily S.
2017-01-01
The line emission properties of non-equilibrium krypton plasma are examined and the optimal emission temperature conditions for soft x-ray emission output in the water-window region are explored. The kinetic parameters for non-equilibrium plasma including major inelastic ion interaction processes, radiation and emission data are obtained with an approach based on the Hartree-Fock-Slater (HFS) quantum-statistical model and a distorted wave approximation. A nonmaxwellian electron distribution is used as well for calculating collisional rates. At a temperature of 70 eV the emission spectral efficiency for Kr equilibrium plasma is about 10%, and it jumps to a value greater than 70% at 100 eV. A similar spectral efficiency is achieved at a lower temperature e.g. 80 eV in non-equilibrium plasma with 7.5 keV fast electron average energy.
Highly stable aerosol generator
DeFord, Henry S.; Clark, Mark L.
1981-01-01
An improved compressed air nebulizer has been developed such that a uniform aerosol particle size and concentration may be produced over long time periods. This result is achieved by applying a vacuum pressure to the makeup assembly and by use of a vent tube between the atmosphere and the makeup solution. By applying appropriate vacuum pressures to the makeup solution container and by proper positioning of the vent tube, a constant level of aspirating solution may be maintained within the aspirating assembly with aspirating solution continuously replaced from the makeup solution supply. This device may also be adapted to have a plurality of aerosol generators and only one central makeup assembly.
Highly stable aerosol generator
DeFord, H.S.; Clark, M.L.
1981-11-03
An improved compressed air nebulizer has been developed such that a uniform aerosol particle size and concentration may be produced over long time periods. This result is achieved by applying a vacuum pressure to the makeup assembly and by use of a vent tube between the atmosphere and the makeup solution. By applying appropriate vacuum pressures to the makeup solution container and by proper positioning of the vent tube, a constant level of aspirating solution may be maintained within the aspirating assembly with aspirating solution continuously replaced from the makeup solution supply. This device may also be adapted to have a plurality of aerosol generators and only one central makeup assembly. 2 figs.
Equilibrium and Non-Equilibrium Condensation Phenomena in Tuneable 3D and 2D Bose Gases
2016-04-01
equilibrium and non-equilibrium many-body phenomena, trapping ultracold atomic gases in different geometries including both 3 and 2 spatial dimensions...box trap we created the world’s first atomic BEC in a quasi-uniform potential. 15. SUBJECT TERMS EOARD, Bose gas, ultracold, condensation, equilibrium... atom trap, Bose-Einstein condensate 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT SAR 18. NUMBER OF PAGES 3 19a. NAME OF RESPONSIBLE
Solvent influence on conformational equilibrium in 3-nitrobenzaldehyde
NASA Astrophysics Data System (ADS)
Konopacka, A.; Kalenik, J.; Pawełka, Z.
2004-11-01
Semi-empirical (PM3, AM1) and ab initio (B3LYP/6-31G(d,p)) calculations of the structure and energies of isolated 3-nitrobenzaldehyde (3-NBA) reveal that the planar trans and cis isomers are in equilibrium, with the trans being more stable by about 2.2 kJ/mol. The experimental dipole moments of 3-NBA in solvents of dielectric permittivity ɛ ranging from 1.9 to 25 have been determined. The increase in the mean dipole moment with increasing ɛ can be well explained in terms of the trans⇔ cis equilibrium and dipolar isomer-solvent interaction. The heterogeneous dielectric medium model with two concentric dielectric layers proved to be the best description for this interaction. On the other hand, the intrinsic experimental Gibbs energy for the trans⇔ cis conversion obtained from this model was higher than the quantum-chemical values. It is suggested that the quadrupolar interaction acts oppositely to the dipolar one stabilizing the more quadrupolar trans isomer.
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.
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.
The non-equilibrium phase diagrams of flow-induced crystallization and melting of polyethylene
NASA Astrophysics Data System (ADS)
Wang, Zhen; Ju, Jianzhu; Yang, Junsheng; Ma, Zhe; Liu, Dong; Cui, Kunpeng; Yang, Haoran; Chang, Jiarui; Huang, Ningdong; Li, Liangbin
2016-09-01
Combining extensional rheology with in-situ synchrotron ultrafast x-ray scattering, we studied flow-induced phase behaviors of polyethylene (PE) in a wide temperature range up to 240 °C. Non-equilibrium phase diagrams of crystallization and melting under flow conditions are constructed in stress-temperature space, composing of melt, non-crystalline δ, hexagonal and orthorhombic phases. The non-crystalline δ phase is demonstrated to be either a metastable transient pre-order for crystallization or a thermodynamically stable phase. Based on the non-equilibrium phase diagrams, nearly all observations in flow-induced crystallization (FIC) of PE can be well understood. The interplay of thermodynamic stabilities and kinetic competitions of the four phases creates rich kinetic pathways for FIC and diverse final structures. The non-equilibrium flow phase diagrams provide a detailed roadmap for precisely processing of PE with designed structures and properties.
The non-equilibrium phase diagrams of flow-induced crystallization and melting of polyethylene
Wang, Zhen; Ju, Jianzhu; Yang, Junsheng; Ma, Zhe; Liu, Dong; Cui, Kunpeng; Yang, Haoran; Chang, Jiarui; Huang, Ningdong; Li, Liangbin
2016-01-01
Combining extensional rheology with in-situ synchrotron ultrafast x-ray scattering, we studied flow-induced phase behaviors of polyethylene (PE) in a wide temperature range up to 240 °C. Non-equilibrium phase diagrams of crystallization and melting under flow conditions are constructed in stress-temperature space, composing of melt, non-crystalline δ, hexagonal and orthorhombic phases. The non-crystalline δ phase is demonstrated to be either a metastable transient pre-order for crystallization or a thermodynamically stable phase. Based on the non-equilibrium phase diagrams, nearly all observations in flow-induced crystallization (FIC) of PE can be well understood. The interplay of thermodynamic stabilities and kinetic competitions of the four phases creates rich kinetic pathways for FIC and diverse final structures. The non-equilibrium flow phase diagrams provide a detailed roadmap for precisely processing of PE with designed structures and properties. PMID:27609305
Relaxed equilibrium configurations to model fossil fields . I. A first family
NASA Astrophysics Data System (ADS)
Duez, V.; Mathis, S.
2010-07-01
Context. The understanding of fossil fields' origin, topology, and stability is one of the corner stones of the stellar magnetism theory. On one hand, since they survive on secular time scales, they may modify the structure and the evolution of their host stars. On the other hand, they must have a complex stable structure since it has been demonstrated that the simplest purely poloidal or toroidal fields are unstable on dynamical time scales. In this context, the only stable configuration found today is the one resulting from a numerical simulation by Braithwaite and collaborators who studied the evolution of an initial stochastic magnetic field, which is found to relax on a mixed stable configuration (poloidal and toroidal) that seems to be in equilibrium and then diffuses. Aims: We investigate an equilibrium field in a semi-analytical way. In this first article, we study the barotropic magnetohydrostatic equilibrium states. Methods: The problem reduces to a Grad-Shafranov-like equation with arbitrary functions. These functions are constrained by deriving the lowest-energy equilibrium states for given invariants of the considered axisymmetric problem, in particular for a given helicity known to be one of the causes of such problems. These theoretical results were applied to realistic stellar cases, the solar radiative core and the envelope of an Ap star, and discussed. In both cases we assumed that the field is initially confined in the stellar radiation zone. Results: The generalization of the force-free Taylor's relaxation states studied in laboratory experiments (in spheromaks) that become non force-free in the self-gravitating stellar case are obtained. The case of general baroclinic equilibrium states will be studied in Paper II.
A new climate-vegetation equilibrium state for Tropical South America
NASA Astrophysics Data System (ADS)
Oyama, Marcos Daisuke; Nobre, Carlos Afonso
2003-12-01
The existence of multiple climate-vegetation equilibria in Tropical South America is investigated under present-day climate conditions with the use of an atmospheric general circulation model coupled to a potential vegetation model. Two stable equilibria were found. One corresponds to the current biome distribution. The second is a new equilibrium state: savannas replace eastern Amazonian forests and a semi-desert area appears in the driest portion of Northeast Brazil. If sustainable development and conservation policies were not able to halt the increasing environmental degradation in those areas, then land use changes could, per se, tip the climate-vegetation system towards this new alternative drier stable equilibrium state, with savannization of parts of Amazonia and desertification of the driest area of Northeast Brazil, and with potential adverse impacts on the rich species diversity in the former region and water resources in the latter.
Stability of the equilibrium for atomic H in solid H2
NASA Technical Reports Server (NTRS)
Rosen, G.
1977-01-01
The previously reported phenomenological rate process theory for the storage of atomic hydrogen free radicals in a tritium-impregnated crystalline molecular hydrogen solid is used to determine the dynamical stability of the constant uniform equilibrium solution. The analysis indicates that the equilibrium is unstable (thus, unattainable experimentally) for storage temperatures in a certain range (specifically between 0.134 and 0.80 K for 0.03% tritium by weight, and between 0.165 and 0.80 K for 1.20% tritium by weight), while being absolutely stable with respect to arbitrary small-amplitude perturbations for all storage temperatures below and above this range. The theory also predicts the maximum size for a stable H/H2 sample with an appreciable concentration of trapped H and a net excess rate of volumetric heating due to the tritium decay.
On equilibrium structures of the water molecule
NASA Astrophysics Data System (ADS)
Császár, Attila G.; Czakó, Gábor; Furtenbacher, Tibor; Tennyson, Jonathan; Szalay, Viktor; Shirin, Sergei V.; Zobov, Nikolai F.; Polyansky, Oleg L.
2005-06-01
Equilibrium structures are fundamental entities in molecular sciences. They can be inferred from experimental data by complicated inverse procedures which often rely on several assumptions, including the Born-Oppenheimer approximation. Theory provides a direct route to equilibrium geometries. A recent high-quality ab initio semiglobal adiabatic potential-energy surface (PES) of the electronic ground state of water, reported by Polyansky et al. [Polyansky et al.Science 299, 539 (2003)] and called CVRQD here, is analyzed in this respect. The equilibrium geometries resulting from this direct route are deemed to be of higher accuracy than those that can be determined by analyzing experimental data. Detailed investigation of the effect of the breakdown of the Born-Oppenheimer approximation suggests that the concept of an isotope-independent equilibrium structure holds to about 3×10-5Å and 0.02° for water. The mass-independent [Born-Oppenheimer (BO)] equilibrium bond length and bond angle on the ground electronic state PES of water is reBO=0.95782Å and θeBO=104.485°, respectively. The related mass-dependent (adiabatic) equilibrium bond length and bond angle of H2O16 is read=0.95785Å and θead=104.500°, respectively, while those of D2O16 are read=0.95783Å and θead=104.490°. Pure ab initio prediction of J =1 and 2 rotational levels on the vibrational ground state by the CVRQD PESs is accurate to better than 0.002cm-1 for all isotopologs of water considered. Elaborate adjustment of the CVRQD PESs to reproduce all observed rovibrational transitions to better than 0.05cm-1 (or the lower ones to better than 0.0035cm-1) does not result in noticeable changes in the adiabatic equilibrium structure parameters. The expectation values of the ground vibrational state rotational constants of the water isotopologs, computed in the Eckart frame using the CVRQD PESs and atomic masses, deviate from the experimentally measured ones only marginally, especially for A0 and B0. The
NASA Astrophysics Data System (ADS)
Kanke, Masaki; Sasaki, Kazuo
2013-09-01
Equilibrium configuration of order parameter in a nematic liquid crystal droplet with homeotropic anchoring of finite strength at the surface is studied numerically by using the Landau--de Gennes approach. It is found that a hedgehog-like configuration with a disclination loop of a small radius is stable for strong anchoring while an axial configuration without defect is stable for weak anchoring. A first-order phase transition from one configuration to the other occurs as the strength of the anchoring is varied. The critical anchoring strength turns out to increase almost linearly with the inverse of the droplet radius.
2007-05-01
The latest version of the NHS Institute for Innovation and Improvement's 'no delays achiever', a web based tool created to help NHS organisations achieve the 18-week target for GP referrals to first treatment, is available at www.nodelaysachiever.nhs.uk.
Vicarious Achievement Orientation.
ERIC Educational Resources Information Center
Leavitt, Harold J.; And Others
This study tests hypotheses about achievement orientation, particularly vicarious achievement. Undergraduate students (N=437) completed multiple-choice questionnaires, indicating likely responses of one person to the success of another. The sex of succeeder and observer, closeness of relationship, and setting (medical school or graduate school of…
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…
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…
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…
Aerospace Applications of Non-Equilibrium Plasma
NASA Technical Reports Server (NTRS)
Blankson, Isaiah M.
2016-01-01
Nonequilibrium plasma/non-thermal plasma/cold plasmas are being used in a wide range of new applications in aeronautics, active flow control, heat transfer reduction, plasma-assisted ignition and combustion, noise suppression, and power generation. Industrial applications may be found in pollution control, materials surface treatment, and water purification. In order for these plasma processes to become practical, efficient means of ionization are necessary. A primary challenge for these applications is to create a desired non-equilibrium plasma in air by preventing the discharge from transitioning into an arc. Of particular interest is the impact on simulations and experimental data with and without detailed consideration of non-equilibrium effects, and the consequences of neglecting non-equilibrium. This presentation will provide an assessment of the presence and influence of non-equilibrium phenomena for various aerospace needs and applications. Specific examples to be considered will include the forward energy deposition of laser-induced non-equilibrium plasmoids for sonic boom mitigation, weakly ionized flows obtained from pulsed nanosecond discharges for an annular Hall type MHD generator duct for turbojet energy bypass, and fundamental mechanisms affecting the design and operation of novel plasma-assisted reactive systems in dielectric liquids (water purification, in-pipe modification of fuels, etc.).
Punctuated equilibrium as an emergent process and its modified thermodynamic characterization.
Wosniack, M E; Luz, M G E da; Schulman, L S
2016-10-27
We address evolutionary dynamics and consider under which conditions the ecosystem interaction network allows punctuated equilibrium (i.e., alternation between hectic and quasi-stable phases). We focus on the links connecting various species and on the strength and sign of those links. For this study we consider the Tangled Nature model, which allows considerable flexibility and plasticity in the analysis of interspecies interactions. We find that it is necessary to have a proper balance of connectivity and interaction intensities so as to establish the kind of mutual cooperation and competition found in nature. It suggests evolutionary punctuated equilibrium as an emergent process, thus displaying features of complex systems. To explicitly demonstrate this fact we consider an extended form of thermodynamics, defining (for the present context) relevant out-of-equilibrium "collective" functions. We then show how to characterize the punctuated equilibrium through entropy-like and free energy-like quantities. Finally, from a close analogy to thermodynamic systems, we propose a protocol similar to simulated annealing. It is based on controlling the species' rate of mutation during the hectic periods, in this way enhancing the exploration of the genome space (similar to the known behavior of bacteria in stressful environments). This allows the system to more rapidly converge to long-duration quasi-stable phases.
Punctuated equilibrium as an emergent process and its modified thermodynamic characterization.
Wosniack, M E; da Luz, M G E; Schulman, L S
2017-01-07
We address evolutionary dynamics and consider under which conditions the ecosystem interaction network allows punctuated equilibrium (i.e., alternation between hectic and quasi-stable phases). We focus on the links connecting various species and on the strength and sign of those links. For this study we consider the Tangled Nature model, which allows considerable flexibility and plasticity in the analysis of interspecies interactions. We find that it is necessary to have a proper balance of connectivity and interaction intensities so as to establish the kind of mutual cooperation and competition found in nature. It suggests evolutionary punctuated equilibrium as an emergent process, thus displaying features of complex systems. To explicitly demonstrate this fact we consider an extended form of thermodynamics, defining (for the present context) relevant out-of-equilibrium "collective" functions. We then show how to characterize the punctuated equilibrium through entropy-like and free energy-like quantities. Finally, from a close analogy to thermodynamic systems, we propose a protocol similar to simulated annealing. It is based on controlling the species' rate of mutation during the hectic periods, in this way enhancing the exploration of the genome space (similar to the known behavior of bacteria in stressful environments). This allows the system to more rapidly converge to long-duration quasi-stable phases.
Rekharsky, Mikhail V; Mori, Tadashi; Yang, Cheng; Ko, Young Ho; Selvapalam, N; Kim, Hyunuk; Sobransingh, David; Kaifer, Angel E; Liu, Simin; Isaacs, Lyle; Chen, Wei; Moghaddam, Sarvin; Gilson, Michael K; Kim, Kimoon; Inoue, Yoshihisa
2007-12-26
The molecular host cucurbit[7]uril forms an extremely stable inclusion complex with the dicationic ferrocene derivative bis(trimethylammoniomethyl)ferrocene in aqueous solution. The equilibrium association constant for this host-guest pair is 3 x 10(15) M(-1) (K(d) = 3 x 10(-16) M), equivalent to that exhibited by the avidin-biotin pair. Although purely synthetic systems with larger association constants have been reported, the present one is unique because it does not rely on polyvalency. Instead, it achieves its extreme affinity by overcoming the compensatory enthalpy-entropy relationship usually observed in supramolecular complexes. Its disproportionately low entropic cost is traced to extensive host desolvation and to the rigidity of both the host and the guest.
Dark halos and elliptical galaxies as marginally stable dynamical systems
El Zant, A. A.
2013-12-10
The origin of equilibrium gravitational configurations is sought in terms of the stability of their trajectories, as described by the curvature of their Lagrangian configuration manifold of particle positions—a context in which subtle spurious effects originating from the singularity in the two-body potential become particularly clear. We focus on the case of spherical systems, which support only regular orbits in the collisionless limit, despite the persistence of local exponential instability of N-body trajectories in the anomalous case of discrete point particle representation even as N → ∞. When the singularity in the potential is removed, this apparent contradiction disappears. In the absence of fluctuations, equilibrium configurations generally correspond to positive scalar curvature and thus support stable trajectories. A null scalar curvature is associated with an effective, averaged equation of state describing dynamically relaxed equilibria with marginally stable trajectories. The associated configurations are quite similar to those of observed elliptical galaxies and simulated cosmological halos and are necessarily different from the systems dominated by isothermal cores, expected from entropy maximization in the context of the standard theory of violent relaxation. It is suggested that this is the case because a system starting far from equilibrium does not reach a 'most probable state' via violent relaxation, but that this process comes to an end as the system finds and (settles in) a configuration where it can most efficiently wash out perturbations. We explicitly test this interpretation by means of direct simulations.
NASA Technical Reports Server (NTRS)
Harm, D. L.; Taylor, L. C.
2006-01-01
Virtual environments offer unique training opportunities, particularly for training astronauts and preadapting them to the novel sensory conditions of microgravity. Two unresolved human factors issues in virtual reality (VR) systems are: 1) potential "cybersickness", and 2) maladaptive sensorimotor performance following exposure to VR systems. Interestingly, these aftereffects are often quite similar to adaptive sensorimotor responses observed in astronauts during and/or following space flight. Changes in the environmental sensory stimulus conditions and the way we interact with the new stimuli may result in motion sickness, and perceptual, spatial orientation and sensorimotor disturbances. Initial interpretation of novel sensory information may be inappropriate and result in perceptual errors. Active exploratory behavior in a new environment, with resulting feedback and the formation of new associations between sensory inputs and response outputs, promotes appropriate perception and motor control in the new environment. Thus, people adapt to consistent, sustained alterations of sensory input such as those produced by microgravity, unilateral labyrinthectomy and experimentally produced stimulus rearrangements. Adaptation is revealed by aftereffects including perceptual disturbances and sensorimotor control disturbances. The purpose of the current study was to compare disturbances in postural control produced by dome and head-mounted virtual environment displays, and to examine the effects of exposure duration, and repeated exposures to VR systems. Forty-one subjects (21 men, 20 women) participated in the study with an age range of 21-49 years old. One training session was completed in order to achieve stable performance on the posture and VR tasks before participating in the experimental sessions. Three experimental sessions were performed each separated by one day. The subjects performed a navigation and pick and place task in either a dome or head-mounted display
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
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.
Interfaces at equilibrium: A guide to fundamentals.
Marmur, Abraham
2016-05-20
The fundamentals of the thermodynamics of interfaces are reviewed and concisely presented. The discussion starts with a short review of the elements of bulk thermodynamics that are also relevant to interfaces. It continues with the interfacial thermodynamics of two-phase systems, including the definition of interfacial tension and adsorption. Finally, the interfacial thermodynamics of three-phase (wetting) systems is discussed, including the topic of non-wettable surfaces. A clear distinction is made between equilibrium conditions, in terms of minimizing energies (internal, Gibbs or Helmholtz), and equilibrium indicators, in terms of measurable, intrinsic properties (temperature, chemical potential, pressure). It is emphasized that the equilibrium indicators are the same whatever energy is minimized, if the boundary conditions are properly chosen. Also, to avoid a common confusion, a distinction is made between systems of constant volume and systems with drops of constant volume.
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.
KSTAR Equilibrium Reconstruction with EFIT Code
NASA Astrophysics Data System (ADS)
You, Kwang-Il; Lee, D. K.; Hahn, S. H.; Lao, L. L.
2007-11-01
For application to the KSTAR (Korea Superconducting Tokamak Advanced Research) device, we have made some modification to the EFIT code and installed it on our computing system. The main function of EFIT is reconstruction of plasma equilibrium using discharge data. After every discharge, the code will be automatically run for a chosen time array and the results will be stored in the same way as experimental data will be. An MDSplus system will be used as the data storage for KSTAR; therefore, the EFIT reads experimental data from the MDSplus server and writes the results to it. We have added some subroutines to EFIT for direct link with the MDSplus server and also converted EFIT to Fortran 95 form. Test runs of the code will be made by using plasma simulator in the KSTAR plasma control system. This paper will also present some results of equilibrium data obtained with the equilibrium mode of EFIT.
Equilibrium reconstruction using EFIT code for KSTAR
NASA Astrophysics Data System (ADS)
You, Kwang-Il; Lee, D. K.; Jeon, Y. M.; Hahn, S. H.; Lao, L. L.
2006-10-01
For application to the KSTAR (Korea Superconducting Tokamak Advanced Research) device, we have made some modification to the EFIT code and installed it on our computing system. The main function of EFIT is reconstruction of plasma equilibrium using discharge data. After every discharge, the code will be run for a chosen time array and the results will be stored in the same way as experimental data will be. An MDSplus system will be used as the data storage for KSTAR; therefore, the EFIT reads experimental data from the MDSplus server and writes the results to it. We have added some subroutines to EFIT for direct link with the MDSplus server and also converted it to Fortran 95 form. Test runs of the code will be made by using the KSTAR plasma control system. This paper will also present results of equilibrium data obtained with the equilibrium mode of EFIT.
Gravitational stability computed through the limit equilibrium method revisited
NASA Astrophysics Data System (ADS)
Tinti, Stefano; Manucci, Anna
2006-01-01
The stability of slopes is a problem of great relevance for geologists and geophysicists as well as for geotechnical and geoenvironmental engineers. The classical approaches are the method of limit equilibrium, and the finite-element and finite-difference analyses of deformations. Since the former is computationally simpler and less expensive, it is more widely used in common practice, though it has some weakness points from a theoretical point of view. Essential in this technique is the definition and computation of the factor of safety F for the slope, a parameter indicating that the slope is stable, if it is larger than unity. The method is known to have not a unique solution, but it is common belief that the safety factors associated with all the solutions fulfilling the basic equilibrium equations do not differ more than 5-10 per cent from each other, which is a range of variability considered acceptable by most. Here the non-uniqueness of the solution is discussed, and it is shown that the magnitude range of F can be so large as to undermine the meaning of the safety factor criterion. The classical limit equilibrium methods based on the assumptions of cutting the sliding body into a set of vertical slices are revised, and the new concept of minimum lithostatic deviation (MLD) is introduced as a means to mitigate the effect of non-uniqueness. The paper suggests that the proper solution to the problem is the one that satisfies the equilibrium equations and minimizes the lithostatic deviation that is defined here as the ratio of the average intensity of the interslice forces and the total weight of the body. Accordingly, the factor of safety F associated with such a solution is suggested to be the value appropriate to evaluate the stability of the slope. Remarkably, the MLD principle gives us the means to introduce a completely revolutionary approach to study stability. We derive expressions that account for gravitational loading, and for additional effects such
Achievability for telerobotic systems
NASA Astrophysics Data System (ADS)
Kress, Reid L.; Draper, John V.; Hamel, William R.
2001-02-01
Methods are needed to improve the capabilities of autonomous robots to perform tasks that are difficult for contemporary robots, and to identify those tasks that robots cannot perform. Additionally, in the realm of remote handling, methods are needed to assess which tasks and/or subtasks are candidates for automation. We are developing a new approach to understanding the capability of autonomous robotic systems. This approach uses formalized methods for determining the achievability of tasks for robots, that is, the likelihood that an autonomous robot or telerobot can successfully complete a particular task. Any autonomous system may be represented in achievability space by the volume describing that system's capabilities within the 3-axis space delineated by perception, cognition, and action. This volume may be thought of as a probability density with achievability decreasing as the distance from the centroid of the volume increases. Similarly, any task may be represented within achievability space. However, as tasks have more finite requirements for perception, cognition, and action, each may be represented as a point (or, more accurately, as a small sphere) within achievability space. Analysis of achievability can serve to identify, a priori, the survivability of robotic systems and the likelihood of mission success; it can be used to plan a mission or portions of a mission; it can be used to modify a mission plan to accommodate unpredicted occurrences; it can also serve to identify needs for modifications to robotic systems or tasks to improve achievability. .
Kinetics and Equilibrium of Age-Induced Precipitation in Cu-4 At. Pct Ti Binary Alloy
NASA Astrophysics Data System (ADS)
Semboshi, Satoshi; Amano, Shintaro; Fu, Jie; Iwase, Akihiro; Takasugi, Takayuki
2017-01-01
Transformation kinetics and phase equilibrium of metastable and stable precipitates in age-hardenable Cu-4 at. pct Ti binary alloy have been investigated by monitoring the microstructural evolution during isothermal aging at temperatures between 693 K (420 °C) and 973 K (700 °C). The microstructure of the supersaturated solid solution evolves in four stages: compositional modulation due to spinodal decomposition, continuous precipitation of the needle-shaped metastable β'-Cu4Ti with a tetragonal structure, discontinuous precipitation of cellular components containing stable β-Cu4Ti lamellae with an orthorhombic structure, and eventually precipitation saturation at equilibrium. In specimens aged below 923 K (650 °C), the stable β-Cu4Ti phase is produced only due to the cellular reaction, whereas it can be also directly obtained from the intergranular needle-shaped β'-Cu4Ti precipitates in specimens aged at 973 K (700 °C). The precipitation kinetics and phase equilibrium observed for the specimens aged between 693 K (420 °C) and 973 K (700 °C) were characterized in accordance with a time-temperature-transformation (TTT) diagram and a Cu-Ti partial phase diagram, which were utilized to determine the alloy microstructure, strength, and electrical conductivity.
Kinetics and Equilibrium of Age-Induced Precipitation in Cu-4 At. Pct Ti Binary Alloy
NASA Astrophysics Data System (ADS)
Semboshi, Satoshi; Amano, Shintaro; Fu, Jie; Iwase, Akihiro; Takasugi, Takayuki
2017-03-01
Transformation kinetics and phase equilibrium of metastable and stable precipitates in age-hardenable Cu-4 at. pct Ti binary alloy have been investigated by monitoring the microstructural evolution during isothermal aging at temperatures between 693 K (420 °C) and 973 K (700 °C). The microstructure of the supersaturated solid solution evolves in four stages: compositional modulation due to spinodal decomposition, continuous precipitation of the needle-shaped metastable β'-Cu4Ti with a tetragonal structure, discontinuous precipitation of cellular components containing stable β-Cu4Ti lamellae with an orthorhombic structure, and eventually precipitation saturation at equilibrium. In specimens aged below 923 K (650 °C), the stable β-Cu4Ti phase is produced only due to the cellular reaction, whereas it can be also directly obtained from the intergranular needle-shaped β'-Cu4Ti precipitates in specimens aged at 973 K (700 °C). The precipitation kinetics and phase equilibrium observed for the specimens aged between 693 K (420 °C) and 973 K (700 °C) were characterized in accordance with a time-temperature-transformation (TTT) diagram and a Cu-Ti partial phase diagram, which were utilized to determine the alloy microstructure, strength, and electrical conductivity.
The transformation dynamics towards equilibrium in non-equilibrium w/w/o double emulsions
NASA Astrophysics Data System (ADS)
Chao, Youchuang; Mak, Sze Yi; Shum, Ho Cheung
2016-10-01
We use a glass-based microfluidic device to generate non-equilibrium water-in-water-in-oil (w/w/o) double emulsions and study how they transform into equilibrium configurations. The method relies on using three immiscible liquids, with two of them from the phase-separated aqueous two-phase systems. We find that the transformation is accompanied by an expansion rim, while the characteristic transformation speed of the rim mainly depends on the interfacial tension between the innermost and middle phases, as well as the viscosity of the innermost phase when the middle phase is non-viscous. Remarkably, the viscosity of the outermost phase has little effect on the transformation speed. Our results account for the dynamics of non-equilibrium double emulsions towards their equilibrium structure and suggest a possibility to utilize the non-equilibrium drops to synthesize functional particles.
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…
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.
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)
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.
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.
Equilibrium properties of hybrid field reversed configurations
NASA Astrophysics Data System (ADS)
Tuszewski, M.; Gupta, D.; Gupta, S.; Onofri, M.; Osin, D.; Deng, B. H.; Dettrick, S. A.; Hubbard, K.; Gota, H.
2017-01-01
Field Reversed Configurations (FRCs) heated by neutral beam injection may include a large fast ion pressure that significantly modifies the equilibrium. A new analysis is required to characterize such hybrid FRCs, as the simple relations used up to now prove inaccurate. The substantial contributions of fast ions to FRC radial pressure balance and diamagnetism are described. A simple model is offered to reconstruct more accurately the equilibrium parameters of elongated hybrid FRCs. Further modeling requires new measurements of either the magnetic field or the plasma pressure.
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).
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
Culture and Achievement Motivation
ERIC Educational Resources Information Center
Maehr, Martin L.
1974-01-01
A framework is suggested for the cross-cultural study of motivation that stresses the importance of contextual conditions in eliciting achievement motivation and emphasizes cultural relativity in the definition of the concept. (EH)
ERIC Educational Resources Information Center
Nevill, Dorothy D.
1975-01-01
Three techniques are outlined for use by higher education institutions to achieve salary equity: salary prediction (using various statistical procedures), counterparting (comparing salaries of persons of similar rank), and grievance procedures. (JT)
Equilibrium instability of chiral mesons in external electromagnetic field via AdS/CFT
NASA Astrophysics Data System (ADS)
Taghavi, Seyed Farid; Vahedi, Ali
2016-06-01
We study the equilibrium instability of chiral quarkonia in a plasma in the presence of constant magnetic and electric field and at finite axial chemical potential using AdS/CFT duality. The model in use is a supersymmetric QCD at large 't Hooft coupling and number of colors. We show that the presence of the magnetic field and the axial chemical potential even in the absence of the electric field make the system unstable. In a gapped system, a stable/unstable equilibrium state phase transition is observed and the initial transition amplitude of the equilibrium state to the non-equilibrium state is investigated. We demonstrate that at zero temperature and large magnetic field the instability grows linearly by increasing the quarkonium binding energy. In the constant electric and magnetic field, the system is in a equilibrium state if the Ohm's law and the chiral magnetic effect cancel their effects. This happens in a sub-space of ( E, B, T, μ 5) space with constraint equation σ B B = - σE, where σ and σ B are electric and chiral magnetic conductivity, respectively. We analyze the decay rate of a gapless system when this constraint is slightly violated.
14 CFR 67.305 - Ear, nose, throat, and equilibrium.
Code of Federal Regulations, 2014 CFR
2014-01-01
... 14 Aeronautics and Space 2 2014-01-01 2014-01-01 false Ear, nose, throat, and equilibrium. 67.305..., nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards for a third-class airman... by, or that may reasonably be expected to be manifested by, vertigo or a disturbance of equilibrium....
46 CFR 42.20-12 - Conditions of equilibrium.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 46 Shipping 2 2011-10-01 2011-10-01 false Conditions of equilibrium. 42.20-12 Section 42.20-12... BY SEA Freeboards § 42.20-12 Conditions of equilibrium. The following conditions of equilibrium are... stability. Through an angle of 20 degrees beyond its position of equilibrium, the vessel must meet...
14 CFR 67.205 - Ear, nose, throat, and equilibrium.
Code of Federal Regulations, 2014 CFR
2014-01-01
... 14 Aeronautics and Space 2 2014-01-01 2014-01-01 false Ear, nose, throat, and equilibrium. 67.205..., nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards for a second-class airman..., vertigo or a disturbance of equilibrium....
14 CFR 67.305 - Ear, nose, throat, and equilibrium.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Ear, nose, throat, and equilibrium. 67.305..., nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards for a third-class airman... by, or that may reasonably be expected to be manifested by, vertigo or a disturbance of equilibrium....
14 CFR 67.105 - Ear, nose, throat, and equilibrium.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Ear, nose, throat, and equilibrium. 67.105..., nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards for a first-class airman... may reasonably be expected to be manifested by, vertigo or a disturbance of equilibrium....
14 CFR 67.205 - Ear, nose, throat, and equilibrium.
Code of Federal Regulations, 2013 CFR
2013-01-01
... 14 Aeronautics and Space 2 2013-01-01 2013-01-01 false Ear, nose, throat, and equilibrium. 67.205..., nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards for a second-class airman..., vertigo or a disturbance of equilibrium....
46 CFR 42.20-12 - Conditions of equilibrium.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 46 Shipping 2 2010-10-01 2010-10-01 false Conditions of equilibrium. 42.20-12 Section 42.20-12... BY SEA Freeboards § 42.20-12 Conditions of equilibrium. The following conditions of equilibrium are... stability. Through an angle of 20 degrees beyond its position of equilibrium, the vessel must meet...
14 CFR 67.105 - Ear, nose, throat, and equilibrium.
Code of Federal Regulations, 2014 CFR
2014-01-01
... 14 Aeronautics and Space 2 2014-01-01 2014-01-01 false Ear, nose, throat, and equilibrium. 67.105..., nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards for a first-class airman... may reasonably be expected to be manifested by, vertigo or a disturbance of equilibrium....
14 CFR 67.305 - Ear, nose, throat, and equilibrium.
Code of Federal Regulations, 2013 CFR
2013-01-01
... 14 Aeronautics and Space 2 2013-01-01 2013-01-01 false Ear, nose, throat, and equilibrium. 67.305..., nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards for a third-class airman... by, or that may reasonably be expected to be manifested by, vertigo or a disturbance of equilibrium....
46 CFR 42.20-12 - Conditions of equilibrium.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 46 Shipping 2 2012-10-01 2012-10-01 false Conditions of equilibrium. 42.20-12 Section 42.20-12... BY SEA Freeboards § 42.20-12 Conditions of equilibrium. The following conditions of equilibrium are... stability. Through an angle of 20 degrees beyond its position of equilibrium, the vessel must meet...
14 CFR 67.305 - Ear, nose, throat, and equilibrium.
Code of Federal Regulations, 2012 CFR
2012-01-01
... 14 Aeronautics and Space 2 2012-01-01 2012-01-01 false Ear, nose, throat, and equilibrium. 67.305..., nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards for a third-class airman... by, or that may reasonably be expected to be manifested by, vertigo or a disturbance of equilibrium....
14 CFR 67.105 - Ear, nose, throat, and equilibrium.
Code of Federal Regulations, 2012 CFR
2012-01-01
... 14 Aeronautics and Space 2 2012-01-01 2012-01-01 false Ear, nose, throat, and equilibrium. 67.105..., nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards for a first-class airman... may reasonably be expected to be manifested by, vertigo or a disturbance of equilibrium....
14 CFR 67.205 - Ear, nose, throat, and equilibrium.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Ear, nose, throat, and equilibrium. 67.205..., nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards for a second-class airman..., vertigo or a disturbance of equilibrium....
46 CFR 42.20-12 - Conditions of equilibrium.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 46 Shipping 2 2013-10-01 2013-10-01 false Conditions of equilibrium. 42.20-12 Section 42.20-12... BY SEA Freeboards § 42.20-12 Conditions of equilibrium. The following conditions of equilibrium are... stability. Through an angle of 20 degrees beyond its position of equilibrium, the vessel must meet...
14 CFR 67.105 - Ear, nose, throat, and equilibrium.
Code of Federal Regulations, 2011 CFR
2011-01-01
... 14 Aeronautics and Space 2 2011-01-01 2011-01-01 false Ear, nose, throat, and equilibrium. 67.105..., nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards for a first-class airman... may reasonably be expected to be manifested by, vertigo or a disturbance of equilibrium....
46 CFR 42.20-12 - Conditions of equilibrium.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 46 Shipping 2 2014-10-01 2014-10-01 false Conditions of equilibrium. 42.20-12 Section 42.20-12... BY SEA Freeboards § 42.20-12 Conditions of equilibrium. The following conditions of equilibrium are... stability. Through an angle of 20 degrees beyond its position of equilibrium, the vessel must meet...
14 CFR 67.305 - Ear, nose, throat, and equilibrium.
Code of Federal Regulations, 2011 CFR
2011-01-01
... 14 Aeronautics and Space 2 2011-01-01 2011-01-01 false Ear, nose, throat, and equilibrium. 67.305..., nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards for a third-class airman... by, or that may reasonably be expected to be manifested by, vertigo or a disturbance of equilibrium....
14 CFR 67.205 - Ear, nose, throat, and equilibrium.
Code of Federal Regulations, 2012 CFR
2012-01-01
... 14 Aeronautics and Space 2 2012-01-01 2012-01-01 false Ear, nose, throat, and equilibrium. 67.205..., nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards for a second-class airman..., vertigo or a disturbance of equilibrium....
14 CFR 67.205 - Ear, nose, throat, and equilibrium.
Code of Federal Regulations, 2011 CFR
2011-01-01
... 14 Aeronautics and Space 2 2011-01-01 2011-01-01 false Ear, nose, throat, and equilibrium. 67.205..., nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards for a second-class airman..., vertigo or a disturbance of equilibrium....
14 CFR 67.105 - Ear, nose, throat, and equilibrium.
Code of Federal Regulations, 2013 CFR
2013-01-01
... 14 Aeronautics and Space 2 2013-01-01 2013-01-01 false Ear, nose, throat, and equilibrium. 67.105..., nose, throat, and equilibrium. Ear, nose, throat, and equilibrium standards for a first-class airman... may reasonably be expected to be manifested by, vertigo or a disturbance of equilibrium....
Stable, Electroinactive Wetting Agent For Fuel Cells
NASA Technical Reports Server (NTRS)
Prakash, Surya G.; Olah, George A.; Narayanan, Sekharipuram R.; Surampudi, Subbarao; Halpert, Gerald
1994-01-01
Straight-chain perfluorooctanesulfonic acid (C8 acid) identified as innocuous and stable wetting agent for use with polytetrafluoroethylene-containing electrodes in liquid-feed direct-oxidation fuel cells suggested for use in vehicles and portable power supplies. C8 acid in small concentrations in aqueous liquid solutions of methanol, trimethoxymethane, dimethoxymethane, and trioxane enables oxidation of these substances by use of commercially available electrodes of type designed originally for use with gases. This function specific to C8 acid molecule and not achieved by other related perfluorolkanesulfonic acids.
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
Sugiura, Haruka; Ito, Manami; Okuaki, Tomoya; Mori, Yoshihito; Kitahata, Hiroyuki; Takinoue, Masahiro
2016-01-20
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.
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.
Group Contribution Methods for Phase Equilibrium Calculations.
Gmehling, Jürgen; Constantinescu, Dana; Schmid, Bastian
2015-01-01
The development and design of chemical processes are carried out by solving the balance equations of a mathematical model for sections of or the whole chemical plant with the help of process simulators. For process simulation, besides kinetic data for the chemical reaction, various pure component and mixture properties are required. Because of the great importance of separation processes for a chemical plant in particular, a reliable knowledge of the phase equilibrium behavior is required. The phase equilibrium behavior can be calculated with the help of modern equations of state or g(E)-models using only binary parameters. But unfortunately, only a very small part of the experimental data for fitting the required binary model parameters is available, so very often these models cannot be applied directly. To solve this problem, powerful predictive thermodynamic models have been developed. Group contribution methods allow the prediction of the required phase equilibrium data using only a limited number of group interaction parameters. A prerequisite for fitting the required group interaction parameters is a comprehensive database. That is why for the development of powerful group contribution methods almost all published pure component properties, phase equilibrium data, excess properties, etc., were stored in computerized form in the Dortmund Data Bank. In this review, the present status, weaknesses, advantages and disadvantages, possible applications, and typical results of the different group contribution methods for the calculation of phase equilibria are presented.
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…
ON THE EQUILIBRIUM STRUCTURE OF SIMPLE LIQUIDS
It is shown that the repulsive (not merely the positive) portion of the Lennard - Jones potential quantitatively dominates the equilibrium structure of...the Lennard - Jones liquid. A simple and accurate approximation for the radial distribution function at high densities is presented.
Phase equilibrium measurements on twelve binary mixtures
Giles, N.F.; Wilson, H.L.; Wilding, W.V.
1996-11-01
Phase equilibrium measurements have been performed on twelve binary mixtures. The PTx method was used to obtain vapor-liquid equilibrium data for the following binary systems at two temperatures each: ethanethiol + propylene; nitrobenzene + methanol; pyridine + ethyl acetate; octane + tert-amyl methyl ether; diisopropyl ether + butane; 1,3-dichloro-2-propanol + epichlorohydrin; 2,3-dichloro-1-propanol + epichlorohydrin; 2,3-epoxy-1-propanol + epichlorohydrin; 3-chloro-1,2-propanediol + epichlorohydrin; methanol + hydrogen cyanide. For these systems, equilibrium vapor and liquid phase compositions were derived from the PTx data using the Soave equation of state to represent the vapor phase and the Wilson, NRTL, or Redlich-Kister activity coefficient model to represent the liquid phase. The infinite dilution activity coefficient of methylamine in N-methyl-2-pyrrolidone was determined at three temperatures by performing PTx measurements on the N-methyl-2-pyrrolidone was determined at three temperatures by performing PTx measurements on the N-methyl-2-pyrrolidone-rich half of the binary. Liquid-liquid equilibrium studies were made on the triethylene glycol + 1-pentene system at two temperatures by directly analyzing samples taken from each liquid phase.
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…
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.
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…
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
Equilibrium molecular thermodynamics from Kirkwood sampling.
Somani, Sandeep; Okamoto, Yuko; Ballard, Andrew J; Wales, David J
2015-05-21
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.
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…
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)
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.
Non-equilibrium spatial dynamics of ecosystems.
Guichard, Frederic; Gouhier, Tarik C
2014-09-01
Ecological systems show tremendous variability across temporal and spatial scales. It is this variability that ecologists try to predict and that managers attempt to harness in order to mitigate risk. However, the foundations of ecological science and its mainstream agenda focus on equilibrium dynamics to describe the balance of nature. Despite a rich body of literature on non-equilibrium ecological dynamics, we lack a well-developed set of predictions that can relate the spatiotemporal heterogeneity of natural systems to their underlying ecological processes. We argue that ecology needs to expand its current toolbox for the study of non-equilibrium ecosystems in order to both understand and manage their spatiotemporal variability. We review current approaches and outstanding questions related to the study of spatial dynamics and its application to natural ecosystems, including the design of reserves networks. We close by emphasizing the importance of ecosystem function as a key component of a non-equilibrium ecological theory, and of spatial synchrony as a central phenomenon for its inference in natural systems.
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.
NASA Astrophysics Data System (ADS)
Shea, Damian; Helz, George R.
1988-07-01
The solubility of covellite has been measured in 0.5-2.0 M NaCl at 25°C. Solutions containing various concentrations of total sulfide and zerovalent sulfur have been studied over the pH range 6-11. The data are interpreted in terms of the following complexes, for which stability constants are presented: CuS(HS) 22-, CuS(HS) 33-, Cu(S 5) 23-, Cu(S 4)(S 5) 3-, and CuS(S 5) 2-. Three of these five species have not been reported before and are probably of importance in anoxic natural waters. The three complexes with the general formula, CuS( X) n, do not display optical absorption spectra characteristic of Cu(II) even though the oxidation state of copper, by convention, is divalent. When Cu 2+ and S 2- combine to form the CuS moiety in these complexes, internal electron transfer from S to Cu occurs. Because polysulfide complexes are extremely stable, the solubility of copper in sulfidic waters is strongly dependent on the activity of solid sulfur, as0. For natural waters, as0 can be calculated from measurements of pH, total zerovalent and total divalent sulfur. At as0 > 0.1, polysulfide complexes (especially CuS(S 5) 2-) are probably the predominant copper species in most sulfidic marine waters. Calculated total copper concentrations in equilibrium with covellite agree satisfactorily with published measurements for some Delaware salt marsh pore waters. This agreement is achieved by postulating that Cu-Fe-S phases, such as chalcopyrite, fail to nucleate at low temperatures in nature.
Thermodynamic Equilibrium and Rise of Complexity in an Accelerated Universe
NASA Astrophysics Data System (ADS)
Moradpour, H.; Riazi, N.
2016-01-01
Observational data (Supernovae type Ia data) indicate that the rate of the universe expansion is increasing, which means that, in the framework of General Relativity, the current phase of the expansion is due to an unknown source of energy. Therefore, the nature of dominated fluid in cosmos, as the source of energy, is mysterious. Here, by considering this property of current accelerating phase along with the concept of thermodynamics equilibrium we try to find possible values for the state parameter ( ω) of the dominated fluid in a ( n+1)-dimensional Friedmann-Robertson-Walker universe. Our results are compatible with previous work for Gauss-Bonnet gravity and point to a universe which is so close to its thermodynamic equilibrium state. By the evolution of the cosmos, the baryonic content of the cosmos is participating in longer range interactions, including gravity and electromagnetism, and structure formation is begun which leads to an increase in the complexity content of the universe. Therefore, a true model for the cosmos should show this rise of complexity and information. In order to achieve this goal, we introduce a simple model including free particles in an expanding box and try to count the number of the states of energy. This configuration shows that the entropy of these number of states as the measure for complexity is increased when dominated fluid satisfies special condition ( ω ≥ -1) which is compatible with the results of the Supernovae type Ia data and the thermodynamic equilibrium conditions. Finally, We see that the rate of increase in the complexity content of the universe increases in the ω → -1 limit.
The Impact of Kitesurfing on the Dynamic Equilibrium
da Luz, Rafael Leonardo Ferreira; da Silva, Fernando Alves; Coertjens, Marcelo
2016-01-01
Background The kitesurfing athletes endure unexpected conditions in terms of the function of irregularities in the surface of the water that requires a correct proprioceptive response in order to maintain equilibrium and execute the required movements while maintaining contact with the board and the water. Objectives The objective of this work was to use the star excursion balance test to compare the dynamic equilibrium of athletes who engage in kitesurfing activities with non-athletic subjects. Methods Fourteen kitesurfing athletes and fifteen sedentary male subjects completed three rounds of the star excursion balance test: familiarity, test one and test two. During each phase the eight directions of the test were performed three times on each leg and the maximum distance reached by the leg (cm) was measured before being divided by the length of the lower limb (%). To compare the intergroup averages, a student test t to independent samples was performed. To compare the averages across the eight directions in the same group, the repeated-measures ANOVA test was employed and to compare the averages of the right leg and the left leg, a student test t to dependent samples was used (α = 0.05). Results For both groups and in both legs, the distance reached in the medial, posteromedial, posterior and posterolateral directions was similar and further than the other directions. It was observed that the athletes in the comparison intergroup achieved superior results than those in the control group in the medial, posteromedial, posterior and posterolateral directions in both right and left legs and the lateral direction in the right leg (P < 0.05). Conclusions Kitesurfing activities result in proportionate adaptations in the dynamic equilibrium of athletes, maybe in function of adaptations in the neuromuscular structure, resulting in a better performance in situations that cause disequilibrium. PMID:28144405
Equilibrium and Sudden Events in Chemical Evolution
NASA Astrophysics Data System (ADS)
Weinberg, David H.; Andrews, Brett H.; Freudenburg, Jenna
2017-03-01
We present new analytic solutions for one-zone (fully mixed) chemical evolution models that incorporate a realistic delay time distribution for Type Ia supernovae (SNe Ia) and can therefore track the separate evolution of α-elements produced by core collapse supernovae (CCSNe) and iron peak elements synthesized in both CCSNe and SNe Ia. Our solutions allow constant, exponential, or linear–exponential ({{te}}-t/{τ {sfh}}) star formation histories, or combinations thereof. In generic cases, α and iron abundances evolve to an equilibrium at which element production is balanced by metal consumption and gas dilution, instead of continuing to increase over time. The equilibrium absolute abundances depend principally on supernova yields and the outflow mass loading parameter η, while the equilibrium abundance ratio [α /{Fe}] depends mainly on yields and secondarily on star formation history. A stellar population can be metal-poor either because it has not yet evolved to equilibrium or because high outflow efficiency makes the equilibrium abundance itself low. Systems with ongoing gas accretion develop metallicity distribution functions (MDFs) that are sharply peaked, while “gas starved” systems with rapidly declining star formation, such as the conventional “closed box” model, have broadly peaked MDFs. A burst of star formation that consumes a significant fraction of a system’s available gas and retains its metals can temporarily boost [α /{Fe}] by 0.1–0.3 dex, a possible origin for rare, α-enhanced stars with intermediate age and/or high metallicity. Other sudden transitions in system properties can produce surprising behavior, including backward evolution of a stellar population from high to low metallicity.
Documenting Reading Achievement and Growth for Students Taking Alternate Assessments
ERIC Educational Resources Information Center
Tindal, Gerald; Nese, Joseph F. T.; Farley, Dan; Saven, Jessica L.; Elliott, Stephen N.
2016-01-01
Students with disabilities have been included in state accountability systems for more than a decade; however, only in the past few years have alternate assessments of alternate achievement standards (AA-AAS) become stable enough to allow examination of these students' achievement growth. Using data from Oregon's AA-AAS in Reading during the…
Stable isotopes in obesity research.
Dolnikowski, Gregory G; Marsh, Julian B; Das, Sai Krupa; Welty, Francine K
2005-01-01
Obesity is recognized as a major public health problem. Obesity is a multifactorial disease and is often associated with a wide range of comorbidities including hypertension, non-insulin dependent (Type II) diabetes mellitus, and cardiovascular disease, all of which contribute to morbidity and mortality. This review deals with stable isotope mass spectrometric methods and the application of stable isotopes to metabolic studies of obesity. Body composition and total energy expenditure (TEE) can be measured by mass spectrometry using stable isotope labeled water, and the metabolism of protein, lipid, and carbohydrate can be measured using appropriate labeled tracer molecules.
Fast convergence to equilibrium for long-chain polymer melts using a MD/continuum hybrid method.
Senda, Yasuhiro; Fujio, Miyuki; Shimamura, Shuji; Blomqvist, Janne; Nieminen, Risto M
2012-10-21
Effective and fast convergence toward an equilibrium state for long-chain polymer melts is realized by a hybrid method coupling molecular dynamics and the elastic continuum. The required simulation time to achieve the equilibrium state is reduced compared with conventional equilibration methods. The polymers move on a wide range phase space due to large-scale fluctuation generated by the elastic continuum. A variety of chain structures is generated in the polymer melt which results in the fast convergence to the equilibrium state.
Equilibrium and non-equilibrium dynamics simultaneously operate in the Galápagos islands.
Valente, Luis M; Phillimore, Albert B; Etienne, Rampal S
2015-08-01
Island biotas emerge from the interplay between colonisation, speciation and extinction and are often the scene of spectacular adaptive radiations. A common assumption is that insular diversity is at a dynamic equilibrium, but for remote islands, such as Hawaii or Galápagos, this idea remains untested. Here, we reconstruct the temporal accumulation of terrestrial bird species of the Galápagos using a novel phylogenetic method that estimates rates of biota assembly for an entire community. We show that species richness on the archipelago is in an ascending phase and does not tend towards equilibrium. The majority of the avifauna diversifies at a slow rate, without detectable ecological limits. However, Darwin's finches form an exception: they rapidly reach a carrying capacity and subsequently follow a coalescent-like diversification process. Together, these results suggest that avian diversity of remote islands is rising, and challenge the mutual exclusivity of the non-equilibrium and equilibrium ecological paradigms.
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
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,…
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,…
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…
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.
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,…
Appraising Reading Achievement.
ERIC Educational Resources Information Center
Ediger, Marlow
To determine quality sequence in pupil progress, evaluation approaches need to be used which guide the teacher to assist learners to attain optimally. Teachers must use a variety of procedures to appraise student achievement in reading, because no one approach is adequate. Appraisal approaches might include: (1) observation and subsequent…
Cognitive Processes and Achievement.
ERIC Educational Resources Information Center
Hunt, Dennis; Randhawa, Bikkar S.
For a group of 165 fourth- and fifth-grade students, four achievement test scores were correlated with success on nine tests designed to measure three cognitive functions: sustained attention, successive processing, and simultaneous processing. This experiment was designed in accordance with Luria's model of the three functional units of the…
Graders' Mathematics Achievement
ERIC Educational Resources Information Center
Bond, John B.; Ellis, Arthur K.
2013-01-01
The purpose of this experimental study was to investigate the effects of metacognitive reflective assessment instruction on student achievement in mathematics. The study compared the performance of 141 students who practiced reflective assessment strategies with students who did not. A posttest-only control group design was employed, and results…
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…
Improving Educational Achievement.
ERIC Educational Resources Information Center
New York University Education Quarterly, 1979
1979-01-01
This is a slightly abridged version of the report of the National Academy of Education panel, convened at the request of HEW Secretary Joseph Califano and Assistant Secretary for Education Mary F. Berry, to study recent declines in student achievement and methods of educational improvement. (SJL)
ERIC Educational Resources Information Center
Rogers, Ibram
2009-01-01
When Gabrielle Carpenter became a guidance counselor in Northern Virginia nine years ago, she focused on the academic achievement gap and furiously tried to close it. At first, she was compelled by tremendous professional interest. However, after seeing her son lose his zeal for school, Carpenter joined forces with other parents to form an…
Achievement in Problem Solving
ERIC Educational Resources Information Center
Friebele, David
2010-01-01
This Action Research Project is meant to investigate the effects of incorporating research-based instructional strategies into instruction and their subsequent effect on student achievement in the area of problem-solving. The two specific strategies utilized are the integration of manipulatives and increased social interaction on a regular basis.…
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…
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…
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…
Equilibrium Initialization and Stability of Three-Dimensional Gas Disks
Wang, Hsiang-Hsu; Klessen, Ralf S.; Dullemond, Cornelis P.; Bosch, Frank C.van den; Fuchs, Burkhard; /KIPAC, Menlo Park
2010-08-25
We present a new systematic way of setting up galactic gas disks based on the assumption of detailed hydrodynamic equilibrium. To do this, we need to specify the density distribution and the velocity field which supports the disk. We first show that the required circular velocity has no dependence on the height above or below the midplane so long as the gas pressure is a function of density only. The assumption of disks being very thin enables us to decouple the vertical structure from the radial direction. Based on that, the equation of hydrostatic equilibrium together with the reduced Poisson equation leads to two sets of second-order non-linear differential equation, which are easily integrated to set-up a stable disk. We call one approach 'density method' and the other one 'potential method'. Gas disks in detailed balance are especially suitable for investigating the onset of the gravitational instability. We revisit the question of global, axisymmetric instability using fully three-dimensional disk simulations. The impact of disk thickness on the disk instability and the formation of spontaneously induced spirals is studied systematically with or without the presence of the stellar potential. In our models, the numerical results show that the threshold value for disk instability is shifted from unity to 0.69 for self-gravitating thick disks and to 0.75 for combined stellar and gas thick disks. The simulations also show that self-induced spirals occur in the correct regions and with the right numbers as predicted by the analytic theory.
Predictable Equilibrium Multichannel Network Characteristizes The Indus River, Pakistan
NASA Astrophysics Data System (ADS)
Carling, Paul
2015-04-01
PREDICTABLE EQUILIBRIUM MULTICHANNEL NETWORK CHARACTERIZES THE INDUS RIVER, PAKISTAN Carling, P.A.1, Trieu, H.1, Hornby, D.2, Darby, S.E.1, Sear, D.A.1, Hutton, C.2, Ali, Z.3, Iqbal, I.3 1Geography & Environment, University of Southampton, Southampton, UK; 2GeoData, University of Southampton, Southampton, UK; 3SUPARCO, Karachi, Pakistan The Indus River in Pakistan between Chasma and Taunsa is a 304 river km reach characterised by islands dividing multiple channels. Previously, the behaviour of such channel networks has been considered unpredictable. Crosato & Mosselman (2009) argue that physics-based predictors of channel splitting developed for braided-river bars apply poorly to island-divided rivers and recommend the application of regime theory (Bettess & White, 1983) to predict the number (n) of channels in rivers such as the Indus. The Indus is characterized by two to 11 channels at each cross section with, on average, about four channels being active during the dry season and five during the monsoon. Thus the expansion of the network during the monsoon is slight and is due to reoccupation of channels that are dry during low flows. The network evolves on an annual basis primarily due to bendway progression, whilst avulsions to form major new channels are relatively rare (one or two in the reach per year) and are matched by a similar number of closures. Thus the network structure, if not its shape, is relatively stable year to year. The standard deviation of channel numbers comparing sections throughout the reach is practically identical at c. two channels and there is no significant variation between years. Theory indicates that stable networks have three to four channels, thus the stability in the number of active channels through the annual monsoon and between years accords with the presence of a near-equilibrium reach-scale channel network that demonstrates local disequilibrium when 3 > n > 4, being perturbed by the annual monsoon. Application of the
Earthquakes in stable continental crust
Johnson, A.C.; Kanter, L.R. )
1990-03-01
Earthquakes can strike even in stable crust, well away from the familiar earthquake zones at the edges of tectonic plates, but their mere occurrence is both a source of concern in planning critical facilities such as nuclear power plants. The authors sought answers to two major questions: Just how much seismic activity does take place within the stable parts of continents And are there specific geologic features that make some areas of stable crust particularly susceptible to earthquakes They began by studying North America alone, but it soon became clear that the fairly short record of these rare events on a single continent would not provide enough data for reliable analysis. Hence, they decided to substitute space for time--to survey earthquake frequency and distribution in stable continental areas worldwide. This paper discusses their findings.
Earthquakes in Stable Continental Crust.
ERIC Educational Resources Information Center
Johnston, Arch C.; Kanter, Lisa R.
1990-01-01
Discussed are some of the reasons for earthquakes which occur in stable crust away from familiar zones at the ends of tectonic plates. Crust stability and the reactivation of old faults are described using examples from India and Australia. (CW)
NASA Astrophysics Data System (ADS)
Tepavitcharova, S.; Havlíček, D.; Matulková, I.; Rabadjieva, D.; Gergulova, R.; Plocek, J.; Němec, I.; Císařová, I.
2016-09-01
Equilibrium crystallization of two anhydrous complex compounds, [Zn(gly)2I2] and [Zn(gly)I2], and non-equilibrium crystallization of the [Zn3(H2O)4(μ-gly)2I6] complex have been observed in the Gly - ZnI2 - H2O system at 25°C. Different mixed zinc-glycine-iodide-aqua complexes exist in the studied solutions and those with the highest activity are responsible for the crystallization process. The stable [ZnI2O2(2Gly)]0 complexes are responsible for the large equilibrium crystallization field of the compound [Zn(gly)2I2] (monoclinic system, C2/c space group), in whose crystal structure they are incorporated as discrete distorted electroneutral tetrahedra. In zinc-iodide solutions with a low water activity it is more probable that the glycine zwitterions act as bidentate ligands and form polynuclear complexes. We assume the [ZnI2O2(2/2Gly)]0 infinite chains build the compound [Zn(gly)I2], for which we have found a narrow equilibrium crystallization field. We have failed to describe the crystal structure of this compound because of its limited stability in the air. Non-equilibrium crystallization of [Zn3(H2O)4(μ-gly)2I6] (triclinic system, P-1 space group) was demonstrated, with crystal structure built by trinuclear complexes [ZnI3O(1/2Gly)] [ZnO4(4H2O)O2(2/2Gly)(trans)][ZnI3O(1/2Gly)]. The FTIR and Raman spectra and also the thermal behaviour of the three compounds were discussed.
Xu, Jiaxing; Sun, Honglin; He, Xuejun; Bai, Zhongzhong; He, Bingfang
2013-02-01
An efficient enzymatic synthesis of endomorphin-2 (EM-2) was achieved using organic solvent stable proteases in nonaqeous media, based on thermodynamic control and an in situ product removal methodology. The high stability of biocatalysts in organic solvents enabled the aleatoric modulation of the nonaqueous reaction media to shift thermodynamic equilibrium toward synthesis. Peptide Boc-Phe-Phe-NH2 was synthesized with a high yield of 96% by the solvent stable protease WQ9-2 in monophase medium with an economical molar ratio of the substrate of 1:1. The tetrapeptide Boc-Tyr-Pro-Phe-Phe-NH2 was synthesized with a yield of 88% by another organic solvent tolerant protease PT121 from Boc-Tyr-Pro-OH and Phe-Phe-NH2 in an organic-aqueous biphasic system. The reaction-separation coupling in both enzymatic processes provides "driving forces" for the synthetic reactions and gives a high yield and high productivity without purification of the intermediate, thereby making the synthesis more amenable to scale-up.
Computation of thermodynamic equilibrium in systems under stress
NASA Astrophysics Data System (ADS)
Vrijmoed, Johannes C.; Podladchikov, Yuri Y.
2016-04-01
pressure. To compute a case of high and low pressure around a stressed inclusion we first did a Finite Element Method calculation of a rigid inclusion in a viscous matrix under simple shear. From the computed stress distribution we took the local pressure (mean stress) in each grid point of the FEM calculation. This was used as input thermodynamic pressure in the Gibbs minimization and the result showed it is possible to have an equilibrium situation in which chlorite-amphibole is stable in the low pressure domain and kyanite in the high pressure domain of the stress field around the inclusion. Interestingly, the calculation predicts the redistribution of fluid from an average content of fluid in the system. The fluid in equilibrium tends to accumulate in the low pressure areas whereas it leaves the high pressure areas dry. Transport of fluid components occurs not necessarily by fluid flow, but may happen for example by diffusion. We conclude that an apparent disequilibrium texture may be explained by equilibrium under pressure variations, and apparent fluid addition by redistribution of fluid controlled by the local stress distribution. [1] Mukai et al. (2014), Journal of Petrology, 55 (8), p. 1457-1477. [2] Holland and Powell (1998), Journal of Metamorphic Geology, 16, p. 309-343 [3] Johnson et al. (1992), Computers & Geosciences, 18 (7), p. 899-947 [4] Connolly (2005), Earth and Planetary Science Letters, 236, p. 524-541
Spectra from pair-equilibrium plasmas
NASA Technical Reports Server (NTRS)
Zdziarski, A. A.
1984-01-01
A numerical model of relativistic nonmagnetized plasma with uniform temperature and electron density distributions is considered, and spectra from plasma in pair equilibrium are studied. A range of dimensionless temperature (T) greater than about 0.2 is considered. The spectra from low pair density plasmas in pair equilibrium vary from un-Comptonized bremsstrahlung spectra at Thomson cross section tau(N) much less than one to Comptonized bremsstrahlung spectra with tau(N) over one. For high pair density plasmas the spectra are flat for T greater than about one, and have broad intensity peaks at energy roughly equal to 3T for T less than one. In the latter region the total luminosity is approximately twice the annihilation luminosity. All spectra are flat in the X-ray region, in contradiction to observed AGN spectra. For dimensionless luminosity greater than about 100, the cooling time becomes shorter than the Thomson time.
Fluctuation theorem for constrained equilibrium systems.
Gilbert, Thomas; Dorfman, J Robert
2006-02-01
We discuss the fluctuation properties of equilibrium chaotic systems with constraints such as isokinetic and Nosé-Hoover thermostats. Although the dynamics of these systems does not typically preserve phase-space volumes, the average phase-space contraction rate vanishes, so that the stationary states are smooth. Nevertheless, finite-time averages of the phase-space contraction rate have nontrivial fluctuations which we show satisfy a simple version of the Gallavotti-Cohen fluctuation theorem, complementary to the usual fluctuation theorem for nonequilibrium stationary states and appropriate to constrained equilibrium states. Moreover, we show that these fluctuations are distributed according to a Gaussian curve for long enough times. Three different systems are considered here: namely, (i) a fluid composed of particles interacting with Lennard-Jones potentials, (ii) a harmonic oscillator with Nosé-Hoover thermostatting, and (iii) a simple hyperbolic two-dimensional map.
Fluctuation theorem for constrained equilibrium systems
NASA Astrophysics Data System (ADS)
Gilbert, Thomas; Dorfman, J. Robert
2006-02-01
We discuss the fluctuation properties of equilibrium chaotic systems with constraints such as isokinetic and Nosé-Hoover thermostats. Although the dynamics of these systems does not typically preserve phase-space volumes, the average phase-space contraction rate vanishes, so that the stationary states are smooth. Nevertheless, finite-time averages of the phase-space contraction rate have nontrivial fluctuations which we show satisfy a simple version of the Gallavotti-Cohen fluctuation theorem, complementary to the usual fluctuation theorem for nonequilibrium stationary states and appropriate to constrained equilibrium states. Moreover, we show that these fluctuations are distributed according to a Gaussian curve for long enough times. Three different systems are considered here: namely, (i) a fluid composed of particles interacting with Lennard-Jones potentials, (ii) a harmonic oscillator with Nosé-Hoover thermostatting, and (iii) a simple hyperbolic two-dimensional map.
Adaptive resolution simulation in equilibrium and beyond
NASA Astrophysics Data System (ADS)
Wang, H.; Agarwal, A.
2015-09-01
In this paper, we investigate the equilibrium statistical properties of both the force and potential interpolations of adaptive resolution simulation (AdResS) under the theoretical framework of grand-canonical like AdResS (GC-AdResS). The thermodynamic relations between the higher and lower resolutions are derived by considering the absence of fundamental conservation laws in mechanics for both branches of AdResS. In order to investigate the applicability of AdResS method in studying the properties beyond the equilibrium, we demonstrate the accuracy of AdResS in computing the dynamical properties in two numerical examples: The velocity auto-correlation of pure water and the conformational relaxation of alanine dipeptide dissolved in water. Theoretical and technical open questions of the AdResS method are discussed in the end of the paper.
Spatial distribution of thermal energy in equilibrium.
Bar-Sinai, Yohai; Bouchbinder, Eran
2015-06-01
The equipartition theorem states that in equilibrium, thermal energy is equally distributed among uncoupled degrees of freedom that appear quadratically in the system's Hamiltonian. However, for spatially coupled degrees of freedom, such as interacting particles, one may speculate that the spatial distribution of thermal energy may differ from the value predicted by equipartition, possibly quite substantially in strongly inhomogeneous or disordered systems. Here we show that for systems undergoing simple Gaussian fluctuations around an equilibrium state, the spatial distribution is universally bounded from above by 1/2k(B)T. We further show that in one-dimensional systems with short-range interactions, the thermal energy is equally partitioned even for coupled degrees of freedom in the thermodynamic limit and that in higher dimensions nontrivial spatial distributions emerge. Some implications are discussed.
Cosmic curvature from de Sitter equilibrium cosmology.
Albrecht, Andreas
2011-10-07
I show that the de Sitter equilibrium cosmology generically predicts observable levels of curvature in the Universe today. The predicted value of the curvature, Ω(k), depends only on the ratio of the density of nonrelativistic matter to cosmological constant density ρ(m)(0)/ρ(Λ) and the value of the curvature from the initial bubble that starts the inflation, Ω(k)(B). The result is independent of the scale of inflation, the shape of the potential during inflation, and many other details of the cosmology. Future cosmological measurements of ρ(m)(0)/ρ(Λ) and Ω(k) will open up a window on the very beginning of our Universe and offer an opportunity to support or falsify the de Sitter equilibrium cosmology.
Equilibrium properties on the EAST superconducting tokamak
NASA Astrophysics Data System (ADS)
Qian, J. P.; Wan, B. N.; Lao, L. L.; Shen, B.; Sabbagh, S. A.; Menard, J.; Sun, Y. W.; Duan, Y. M.; Li, J. H.; Xiao, B. J.; Gong, X. Z.; Gong
2009-06-01
The Experimental Advanced Superconducting Tokamak (EAST) has a major radius of R0 = 1.75 m and a midplane halfwidth of 0.5 m. It has been operated with a toroidal magnetic field B0 = 2 T and Ip ≤ 500 kA. The evolution of the plasma equilibrium is analysed between discharges by Equilibrium Fitting Code (EFIT). Limiter, single-null and double-null diverted configurations have been produced. A plasma elongation in the range 1.3 ≤ κ ≤ 1.9 and a triangularity in the range 0.1 ≤ δ ≤ 0.55 have been sustained. The operation space of elongated discharges is also presented based on the EAST database.
Instability of quantum equilibrium in Bohm's dynamics
Colin, Samuel; Valentini, Antony
2014-01-01
We consider Bohm's second-order dynamics for arbitrary initial conditions in phase space. In principle, Bohm's dynamics allows for ‘extended’ non-equilibrium, with initial momenta not equal to the gradient of phase of the wave function (as well as initial positions whose distribution departs from the Born rule). We show that extended non-equilibrium does not relax in general and is in fact unstable. This is in sharp contrast with de Broglie's first-order dynamics, for which non-standard momenta are not allowed and which shows an efficient relaxation to the Born rule for positions. On this basis, we argue that, while de Broglie's dynamics is a tenable physical theory, Bohm's dynamics is not. In a world governed by Bohm's dynamics, there would be no reason to expect to see an effective quantum theory today (even approximately), in contradiction with observation. PMID:25383020
Phase Equilibrium Investigations of Planetary Materials
NASA Technical Reports Server (NTRS)
Grove, T. L.
2005-01-01
This grant provided funds to carry out phase equilibrium studies on the processes of chemical differentiation of the moon and the meteorite parent bodies, during their early evolutionary history. Several experimental studies examined processes that led to the formation of lunar ultramafic glasses. Phase equilibrium studies were carried out on selected low-Ti and high-Ti lunar ultramafic glass compositions to provide constraints on the depth range, temperature and processes of melt generation and/or assimilation. A second set of experiments examined the role of sulfide melts in core formation processes in the earth and terrestrial planets. The major results of each paper are discussed, and copies of the papers are attached as Appendix I.
Equilibrium Reconstruction of KSTAR First Plasma
NASA Astrophysics Data System (ADS)
You, K.-I.; Lee, D. K.; Park, B. H.; Lee, S. G.; Bak, J. G.; Seo, S. H.; Hahn, S. H.; Lao, L. L.
2008-11-01
To reconstruct the plasma equilibrium of KSTAR (Korea Superconducting Tokamak Advanced Research), we have made some modification to the EFIT code and installed it on our computing system. An MDSplus system is used for the data storage of KSTAR; thus, the EFIT reads experimental data from the MDSplus server and writes the results to it. We have modified some subroutines of the EFIT code for direct link with the MDSplus server. KSTAR PF and TF coil systems use a CICC (Cable-In-Conduit Conductor) type superconductor. The CICC jacket material for most PF and all TF coils is Incoloy 908, which is a magnetic material with relative magnetic permeability greater than 10 in low external field. The Incoloy 908 effects should, therefore, be considered in analyzing the magnetic diagnostics data. In this paper, we present our efforts to reconstruct the plasma equilibrium with EFIT code, including the compensation of Incoloy 908 effects.
Molecular equilibrium with condensation. [in astrophysics
NASA Technical Reports Server (NTRS)
Sharp, C. M.; Huebner, W. F.
1990-01-01
Minimization of the Gibbs energy of formation for species of chemical elements and compounds in their gas and condensed phases determines their relative abundances in a mixture in chemical equilibrium. The procedure is more general and more powerful than previous abundance determinations in multiphase astrophysical mixtures. Some results for astrophysical equations of state are presented, and the effects of condensation on opacity are briefly indicated.
Flux Jacobian Matrices For Equilibrium Real Gases
NASA Technical Reports Server (NTRS)
Vinokur, Marcel
1990-01-01
Improved formulation includes generalized Roe average and extension to three dimensions. Flux Jacobian matrices derived for use in numerical solutions of conservation-law differential equations of inviscid flows of ideal gases extended to real gases. Real-gas formulation of these matrices retains simplifying assumptions of thermodynamic and chemical equilibrium, but adds effects of vibrational excitation, dissociation, and ionization of gas molecules via general equation of state.
Equilibrium Configuration of Φ4 Oscillatons
NASA Astrophysics Data System (ADS)
Valdez-Alvarado, Susana; Becerril, Ricardo; Ureña-López, L. Arturo
2010-07-01
We search for equilibrium configurations of the (coupled) Einstein-Klein-Gordon equations for the case of a real scalar field endowed with a quartic self-interaction potential. The resulting solutions are the generalizations of the (massive) oscillating soliton stars, the so-called oscillatons. Among other parameters, we estimate the mass curve of the configurations, and determine their critical mass for different values of the quartic interaction.
Oxygen equilibrium of brachiopod Lingula hemerythrin.
MANWELL, C
1960-08-26
In contrast to hemerythrin from five different species of sipunculid worms, ecardine brachiopod Lingula hemerythrin has an oxygen equilibrium which is reversibly altered by pH changes, both the oxygen affinity (Bohr effect) and the interactions between oxygen-binding centers being a function of pH. The significance of these phenomena is discussed in view of the phylogenetic distribution of hemerythrin and the function of respiratory pigments.
Stationary equilibrium singularity distributions in the plane
NASA Astrophysics Data System (ADS)
Newton, P. K.; Ostrovskyi, V.
2012-02-01
We characterize all stationary equilibrium point singularity distributions in the plane of logarithmic type, allowing for real, imaginary or complex singularity strengths. The dynamical system follows from the assumption that each of the N singularities moves according to the flow field generated by all the others at that point. For strength vector \\vec{\\Gamma} \\in {\\Bbb R}^N , the dynamical system is the classical point vortex system obtained from a singular discrete representation of the vorticity field from ideal, incompressible fluid flow. When \\vec{\\Gamma} \\in \\Im , it corresponds to a system of sources and sinks, whereas when \\vec{\\Gamma} \\in {\\Bbb C}^N the system consists of spiral sources and sinks discussed in Kochin et al (1964 Theoretical Hydromechanics 1 (London: Interscience)). We formulate the equilibrium problem as one in linear algebra, A \\vec{\\Gamma} = 0 , A \\in {\\Bbb C}^{N \\times N} , \\vec{\\Gamma} \\in {\\Bbb C}^N , where A is a N × N complex skew-symmetric configuration matrix which encodes the geometry of the system of interacting singularities. For an equilibrium to exist, A must have a kernel and \\vec{\\Gamma} must be an element of the nullspace of A. We prove that when N is odd, A always has a kernel, hence there is a choice of \\vec{\\Gamma} for which the system is a stationary equilibrium. When N is even, there may or may not be a non-trivial nullspace of A, depending on the relative position of the points in the plane. We provide examples of evenly and randomly distributed points on curves such as circles, figure eights, flower-petal configurations and spirals. We then show how to classify the stationary equilibria in terms of the singular spectrum of A.
The Dynamical Equilibrium of Galaxy Clusters
NASA Astrophysics Data System (ADS)
Carlberg, R. G.; Yee, H. K. C.; Ellingson, E.; Morris, S. L.; Abraham, R.; Gravel, P.; Pritchet, C. J.; Smecker-Hane, T.; Hartwick, F. D. A.; Hesser, J. E.; Hutchings, J. B.; Oke, J. B.
1997-02-01
If a galaxy cluster is effectively in dynamical equilibrium, then all galaxy populations within the cluster must have distributions in velocity and position that individually reflect the same underlying mass distribution, although the derived virial masses can be quite different. Specifically, within the Canadian Network for Observational Cosmology cluster sample, the virial radius of the red galaxy population is, on the average, a factor of 2.05 +/- 0.34 smaller than that of the blue population. The red galaxies also have a smaller rms velocity dispersion, a factor of 1.31 +/- 0.13 within our sample. Consequently, the virial mass calculated from the blue galaxies is 3.5 +/- 1.3 times larger than from the red galaxies. However, applying the Jeans equation of stellar hydrodynamic equilibrium to the red and blue subsamples separately gives statistically identical cluster mass profiles. This is strong evidence that these clusters are effectively equilibrium systems and therefore demonstrates empirically that the masses in the virialized region are reliably estimated using dynamical techniques.
TEA: A Code Calculating Thermochemical Equilibrium Abundances
NASA Astrophysics Data System (ADS)
Blecic, Jasmina; Harrington, Joseph; Bowman, M. Oliver
2016-07-01
We present an open-source Thermochemical Equilibrium Abundances (TEA) code that calculates the abundances of gaseous molecular species. The code is based on the methodology of White et al. and Eriksson. It applies Gibbs free-energy minimization using an iterative, Lagrangian optimization scheme. Given elemental abundances, TEA calculates molecular abundances for a particular temperature and pressure or a list of temperature-pressure pairs. We tested the code against the method of Burrows & Sharp, the free thermochemical equilibrium code Chemical Equilibrium with Applications (CEA), and the example given by Burrows & Sharp. Using their thermodynamic data, TEA reproduces their final abundances, but with higher precision. We also applied the TEA abundance calculations to models of several hot-Jupiter exoplanets, producing expected results. TEA is written in Python in a modular format. There is a start guide, a user manual, and a code document in addition to this theory paper. TEA is available under a reproducible-research, open-source license via https://github.com/dzesmin/TEA.
Equilibrium Partitioning Sediment Benchmarks (ESBs) for the ...
This document describes procedures to determine the concentrations of nonionic organic chemicals in sediment interstitial waters. In previous ESB documents, the general equilibrium partitioning (EqP) approach was chosen for the derivation of sediment benchmarks because it accounts for the varying bioavailability of chemicals in different sediments and allows for the incorporation of the appropriate biological effects concentration. This provides for the derivation of benchmarks that are causally linked to the specific chemical, applicable across sediments, and appropriately protective of benthic organisms. This equilibrium partitioning sediment benchmark (ESB) document was prepared by scientists from the Atlantic Ecology Division, Mid-Continent Ecology Division, and Western Ecology Division, the Office of Water, and private consultants. The document describes procedures to determine the interstitial water concentrations of nonionic organic chemicals in contaminated sediments. Based on these concentrations, guidance is provided on the derivation of toxic units to assess whether the sediments are likely to cause adverse effects to benthic organisms. The equilibrium partitioning (EqP) approach was chosen because it is based on the concentrations of chemical(s) that are known to be harmful and bioavailable in the environment. This document, and five others published over the last nine years, will be useful for the Program Offices, including Superfund, a
Bifurcated helical core equilibrium states in tokamaks
NASA Astrophysics Data System (ADS)
Cooper, W. A.; Chapman, I. T.; Schmitz, O.; Turnbull, A. D.; Tobias, B. J.; Lazarus, E. A.; Turco, F.; Lanctot, M. J.; Evans, T. E.; Graves, J. P.; Brunetti, D.; Pfefferlé, D.; Reimerdes, H.; Sauter, O.; Halpern, F. D.; Tran, T. M.; Coda, S.; Duval, B. P.; Labit, B.; Pochelon, A.; Turnyanskiy, M. R.; Lao, L.; Luce, T. C.; Buttery, R.; Ferron, J. R.; Hollmann, E. M.; Petty, C. C.; van Zeeland, M.; Fenstermacher, M. E.; Hanson, J. M.; Lütjens, H.
2013-07-01
Tokamaks with weak to moderate reversed central shear in which the minimum inverse rotational transform (safety factor) qmin is in the neighbourhood of unity can trigger bifurcated magnetohydrodynamic equilibrium states, one of which is similar to a saturated ideal internal kink mode. Peaked prescribed pressure profiles reproduce the ‘snake’ structures observed in many tokamaks which has led to a novel explanation of the snake as a bifurcated equilibrium state. Snake equilibrium structures are computed in simulations of the tokamak à configuration variable (TCV), DIII-D and mega amp spherical torus (MAST) tokamaks. The internal helical deformations only weakly modulate the plasma-vacuum interface which is more sensitive to ripple and resonant magnetic perturbations. On the other hand, the external perturbations do not alter the helical core deformation in a significant manner. The confinement of fast particles in MAST simulations deteriorate with the amplitude of the helical core distortion. These three-dimensional bifurcated solutions constitute a paradigm shift that motivates the applications of tools developed for stellarator research in tokamak physics investigations.
Generalized Convective Quasi-Equilibrium Closure
NASA Astrophysics Data System (ADS)
Yano, Jun-Ichi; Plant, Robert
2016-04-01
Arakawa and Schubert proposed convective quasi-equilibrium as a basic principle for closing their spectrum mass-flux convection parameterization. In deriving this principle, they show that the cloud work function is a key variable that controls the growth of convection. Thus, this closure hypothesis imposes a steadiness of the cloud work function tendency. This presentation shows how this principle can be generalized so that it can also encompasses both the CAPE and the moisture-convergence closures. Note that the majority of the current mass-flux convection parameterization invokes a CAPE closure, whereas the moisture-convergence closure was extremely popular historically. This generalization, in turn, includes both closures as special cases of convective quasi-equilibrium. This generalization further suggests wide range of alternative possibilities for convective closure. In general, a vertical integral of any function depending on both large-scale and convective-scale variables can be adopted as an alternative closure variables, leading to an analogous formulation as Arakawa and Schubert's convective quasi-equilibrium formulation. Among those, probably the most fascinating possibility is to take a vertical integral of the convective-scale moisture for the closure. Use of a convective-scale variable for closure has a particular appeal by not suffering from a loss of predictability of any large-scale variables. That is a main problem with any of the current convective closures, not only for the moisture-convergence based closure as often asserted.
Recovery of postural equilibrium control following spaceflight
NASA Technical Reports Server (NTRS)
Paloski, W. H.; Reschke, M. F.; Black, F. O.; Doxey, D. D.; Harm, D. L.
1992-01-01
Decreased postural stability is observed in most astronauts immediately following spaceflight. Because ataxia may present postflight operational hazards, it is important to determine the incidence of postural instability immediately following landing and the dynamics of recovery of normal postural equilibrium control. It is postulated that postflight postural instability results from in-flight adaptive changes in central nervous system (CNS) processing of sensory information from the visual, vestibular, and proprioceptive systems. The purpose of the present investigation was to determine the magnitude and time course of postflight recovery of postural equilibrium control and, hence, readaptation of CNS processing of sensory information. Thirteen crew members from six spaceflight missions were studied pre- and postflight using a modified commercial posturography system. Postural equilibrium control was found to be seriously disrupted immediately following spaceflight in all subjects. Readaptation to the terrestrial environment began immediately upon landing, proceeded rapidly for the first 10-12 hours, and then proceeded much more slowly for the subsequent 2-4 days until preflight stability levels were reachieved. It is concluded that the overall postflight recovery of postural stability follows a predictable time course.
Equilibrium Gold Nanoclusters Quenched with Biodegradable Polymers
Murthy, Avinash K.; Stover, Robert J.; Borwankar, Ameya U.; Nie, Golay D.; Gourisankar, Sai; Truskett, Thomas M.; Sokolov, Konstantin V.; Johnston, Keith P.
2013-01-01
Although sub-100 nm nanoclusters of metal nanoparticles are of interest in many fields including biomedical imaging, sensors and catalysis, it has been challenging to control their morphologies and chemical properties. Herein, a new concept is presented to assemble equilibrium Au nanoclusters of controlled size by tuning the colloidal interactions with a polymeric stabilizer, PLA(1k)-b-PEG(10k)-b-PLA(1k). The nanoclusters form upon mixing a dispersion of ~5 nm Au nanospheres with a polymer solution followed by partial solvent evaporation. A weakly adsorbed polymer quenches the equilibrium nanocluster size and provides steric stabilization. Nanocluster size is tuned from ~20 nm to ~40 nm by experimentally varying the final Au nanoparticle concentration and the polymer/Au ratio, along with the charge on the initial Au nanoparticle surface. Upon biodegradation of the quencher, the nanoclusters reversibly and fully dissociate to individual ~5 nm primary particles. Equilibrium cluster size is predicted semi-quantitatively with a free energy model that balances short-ranged depletion and van der Waals attractions with longer-ranged electrostatic repulsion, as a function of the Au and polymer concentrations. The close spacings of the Au nanoparticles in the clusters produce strong NIR extinction over a broad range of wavelengths from 650 to 900 nm, which is of practical interest in biomedical imaging. PMID:23230905
Piecewise Smooth Dynamical Systems Theory: The Case of the Missing Boundary Equilibrium Bifurcations
NASA Astrophysics Data System (ADS)
Hogan, S. J.; Homer, M. E.; Jeffrey, M. R.; Szalai, R.
2016-10-01
We present two codimension-one bifurcations that occur when an equilibrium collides with a discontinuity in a piecewise smooth dynamical system. These simple cases appear to have escaped recent classifications. We present them here to highlight some of the powerful results from Filippov's book Differential Equations with Discontinuous Righthand Sides (Kluwer, 1988). Filippov classified the so-called boundary equilibrium collisions without providing their unfolding. We show the complete unfolding here, for the first time, in the particularly interesting case of a node changing its stability as it collides with a discontinuity. We provide a prototypical model that can be used to generate all codimension-one boundary equilibrium collisions, and summarize the elements of Filippov's work that are important in achieving a full classification.
Faculty achievement tracking tool.
Pettus, Sarah; Reifschneider, Ellen; Burruss, Nancy
2009-03-01
Faculty development and scholarship is an expectation of nurse educators. Accrediting institutions, such as the Commission on Collegiate Nursing Education, the National League for Nursing Accrediting Commission, and the Higher Learning Commission, all have criteria regarding faculty achievement. A faculty achievement tracking tool (FATT) was developed to facilitate documentation of accreditation criteria attainment. Based on criteria from accrediting organizations, the roles that are addressed include scholarship, service, and practice. Definitions and benchmarks for the faculty as an aggregate are included. Undergoing reviews from different accrediting organizations, the FATT has been used once for accreditation of the undergraduate program and once for accreditation of the graduate program. The FATT is easy to use and has become an excellent adjunct for the preparation for accreditation reports. In addition, the FATT may be used for yearly evaluations, advancement, and merit.
1997-06-13
Project ACHIEVE was a math/science academic enhancement program aimed at first year high school Hispanic American students. Four high schools -- two in El Paso, Texas and two in Bakersfield, California -- participated in this Department of Energy-funded program during the spring and summer of 1996. Over 50 students, many of whom felt they were facing a nightmare future, were given the opportunity to work closely with personal computers and software, sophisticated calculators, and computer-based laboratories -- an experience which their regular academic curriculum did not provide. Math and science projects, exercises, and experiments were completed that emphasized independent and creative applications of scientific and mathematical theories to real world problems. The most important outcome was the exposure Project ACHIEVE provided to students concerning the college and technical-field career possibilities available to them.
Radio Frequency Plasma Discharge Lamps for Use as Stable Calibration Light Sources
NASA Technical Reports Server (NTRS)
McAndrew, Brendan; Cooper, John; Arecchi, Angelo; McKee, Greg; Durell, Christopher
2012-01-01
Stable high radiance in visible and near-ultraviolet wavelengths is desirable for radiometric calibration sources. In this work, newly available electrodeless radio-frequency (RF) driven plasma light sources were combined with research grade, low-noise power supplies and coupled to an integrating sphere to produce a uniform radiance source. The stock light sources consist of a 28 VDC power supply, RF driver, and a resonant RF cavity. The RF cavity includes a small bulb with a fill gas that is ionized by the electric field and emits light. This assembly is known as the emitter. The RF driver supplies a source of RF energy to the emitter. In commercial form, embedded electronics within the RF driver perform a continual optimization routine to maximize energy transfer to the emitter. This optimization routine continually varies the light output sinusoidally by approximately 2% over a several-second period. Modifying to eliminate this optimization eliminates the sinusoidal variation but allows the output to slowly drift over time. This drift can be minimized by allowing sufficient warm-up time to achieve thermal equilibrium. It was also found that supplying the RF driver with a low-noise source of DC electrical power improves the stability of the lamp output. Finally, coupling the light into an integrating sphere reduces the effect of spatial fluctuations, and decreases noise at the output port of the sphere.
The stability of tidal equilibrium for hierarchical star-planet-moon systems
NASA Astrophysics Data System (ADS)
Adams, Fred C.; Bloch, Anthony M.
2016-11-01
Motivated by the current search for exomoons, this paper considers the stability of tidal equilibrium for hierarchical three-body systems containing a star, a planet, and a moon. In this treatment, the energy and angular momentum budgets include contributions from the planetary orbit, lunar orbit, stellar spin, planetary spin, and lunar spin. The goal is to determine the optimized energy state of the system subject to the constraint of constant angular momentum. Because of the lack of a closed form solution for the full three-body problem, however, we must use an approximate description of the orbits. We first consider the Keplerian limit and find that the critical energy states are saddle points, rather than minima, so that these hierarchical systems have no stable tidal equilibrium states. We then generalize the calculation so that the lunar orbit is described by a time-averaged version of the circular restricted three-body problem. In this latter case, the critical energy state is a shallow minimum, so that a tidal equilibrium state exists. In both cases, however, the lunar orbit for the critical point lies outside the boundary (roughly half the Hill radius) where (previous) numerical simulations indicate dynamical instability. These results suggest that star-planet-moon systems have no viable long-term stable states analogous to those found for two-body systems.
Stable Boundary Layer Education (STABLE) Final Campaign Summary
Turner, David D.
2016-03-01
The properties of, and the processes that occur in, the nocturnal stable boundary layer are not well understood, making it difficult to represent adequately in numerical models. The nocturnal boundary layer often is characterized by a temperature inversion and, in the Southern Great Plains region, a low-level jet. To advance our understanding of the nocturnal stable boundary layer, high temporal and vertical resolution data on the temperature and wind properties are needed, along with both large-eddy simulation and cloud-resolving modeling.
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.
NASA Astrophysics Data System (ADS)
Zheng, Yong-Fei; Wang, Zheng-Rong; Li, Shu-Guang; Zhao, Zi-Fu
2002-02-01
Sm-Nd and oxygen isotope analyses were carried out for mineral separates of ultrahigh pressure eclogites from the Sulu terrane in eastern China. The results show a direct correspondence in equilibrium or disequilibrium state between the oxygen and Sm-Nd isotope systems of eclogite minerals. The omphacite-garnet pairs of oxygen isotope equilibrium at eclogite-facies conditions yield meaningful Triassic Sm-Nd isochron ages, whereas those of oxygen isotope disequilibrium give non-Triassic ages of geological meaninglessness. This can be reasonably interpreted by the fact that the rates of oxygen diffusion in garnet and pyroxene are lower than, or close to, those of Nd diffusion, and thus attainment of isotopic equilibrium in the omphacite-garnet O system suggests achievement of Nd isotope equilibrium in the same mineral pairs. The presence or absence of fluid in the eclogite protoliths is a major rate-controlling factor for isotopic equilibration during high-grade metamorphism. It appears that the state of oxygen isotope equilibrium between cogenetic minerals can provide a critical test for the validity of the Sm-Nd mineral chronometer. In addition, the exact timing of the ultrahigh pressure metamorphism in the Dabie-Sulu terranes is constrained at Early Triassic rather than Late Triassic.
On the Equilibrium States of Interconnected Bubbles or Balloons.
ERIC Educational Resources Information Center
Weinhaus, F.; Barker, W.
1978-01-01
Describes the equilibrium states of a system composed of two interconnected, air-filled spherical membranes of different sizes. The equilibrium configurations are determined by the method of minimization of the availability of the system at constant temperature. (GA)
On the Concept "Chemical Equilibrium": The Associative Framework.
ERIC Educational Resources Information Center
Gussarsky, Esther; Gorodetsky, Malka
1990-01-01
Word associations were used to map high school students' concepts of "chemical equilibrium" and "equilibrium." It was found that the preconception of the two concepts was differentiated on noncritical dimensions. (Author/CW)
Thermodynamics and Kinetics of Chemical Equilibrium in Solution.
ERIC Educational Resources Information Center
Leenson, I. A.
1986-01-01
Discusses theory of thermodynamics of the equilibrium in solution and dissociation-dimerization kinetics. Describes experimental procedure including determination of molar absorptivity and equilibrium constant, reaction enthalpy, and kinetics of the dissociation-dimerization reaction. (JM)
Do persistent organic pollutants reach a thermodynamic equilibrium in the global environment?
Schenker, Sebastian; Scheringer, Martin; Hungerbühler, Konrad
2014-05-06
Equilibrium partitioning between different environmental media is one of the main driving forces that govern the environmental fate of organic chemicals. In the global environment, equilibrium partitioning is in competition with long-range transport, advective phase transfer processes such as wet deposition, and degradation. Here we investigate under what conditions equilibrium partitioning is strong enough to control the global distribution of organic chemicals. We use a global multimedia mass-balance model to calculate the Globally Balanced State (GBS) of organic chemicals. The GBS is the state where equilibrium partitioning is in balance with long-range transport; it represents the maximum influence of thermodynamic driving forces on the global distribution of a chemical. Next, we compare the GBS with the Temporal Remote State, which represents the long-term distribution of a chemical in the global environment when the chemical's distribution is influenced by all transport and degradation processes in combination. This comparison allows us to identify the chemical properties required for a substance to reach the GBS as a stable global distribution. We find that thermodynamically controlled distributions are rare and do not occur for most Persistent Organic Pollutants. They are only found for highly volatile and persistent substances, such as chlorofluorocarbons. Furthermore, we find that the thermodynamic cold-trap effect (i.e., accumulation of pollutants at the poles because of reduced vapor pressure at low temperatures) is often strongly attenuated by atmospheric and oceanic long-range transport.
NASA Astrophysics Data System (ADS)
Shiraishi, J.; Aiba, N.; Miyato, N.; Yagi, M.
2014-08-01
Toroidal rotation effects are self-consistently taken into account not only in the linear magnetohydrodynamic (MHD) stability analysis but also in the equilibrium calculation. The MHD equilibrium computation is affected by centrifugal force due to the toroidal rotation. To study the toroidal rotation effects on resistive wall modes (RWMs), a new code has been developed. The RWMaC modules, which solve the electromagnetic dynamics in vacuum and the resistive wall, have been implemented in the MINERVA code, which solves the Frieman-Rotenberg equation that describes the linear ideal MHD dynamics in a rotating plasma. It is shown that modification of MHD equilibrium by the centrifugal force significantly reduces growth rates of RWMs with fast rotation in the order of M2 = 0.1 where M is the Mach number. Moreover, it can open a stable window which does not exist under the assumption that the rotation affects only the linear dynamics. The rotation modifies the equilibrium pressure gradient and current density profiles, which results in the change of potential energy including rotational effects.
Equation of state for {beta}-stable hot nuclear matter
Moustakidis, Ch. C.; Panos, C. P.
2009-04-15
We provide an equation of state for hot nuclear matter in {beta} equilibrium by applying a momentum-dependent effective interaction. We focus on the study of the equation of state of high-density and high-temperature nuclear matter, containing leptons (electrons and muons) under the chemical equilibrium condition in which neutrinos have left the system. The conditions of charge neutrality and equilibrium under the {beta}-decay process lead first to the evaluation of proton and lepton fractions and then to the evaluation of internal energy, free energy, and pressure, and in total to the equation of state of hot nuclear matter. Thermal effects on the properties and equation of state of nuclear matter are assessed and analyzed in the framework of the proposed effective interaction model. Special attention is given to the study of the contribution of the components of {beta}-stable nuclear matter to the entropy per particle, a quantity of great interest in the study of structure and collapse of supernova.
Highly Stable Silver Nanoplates for Surface Plasmon Resonance Biosensing
Gao, Chuanbo; Lu, Zhenda; Chi, Miaofang; Liu, ying; Cheng, Quan; Yin, Yadong
2012-01-01
An SPR biosensor was developed by employing highly stable Au-protected Ag nanoplates (NP) as enhancers (see picture). Superior performance was achieved by depositing a thin and uniform coating of Au on the Ag surface while minimizing disruptive galvanic replacement and retaining the strong surface plasmon resonance (SPR) of the silver nanoplates.
Fabrication of stable polyaniline foams and their photoelectric conversion behaviors.
Heng, Liping; Wang, Xinyi; Zhai, Jin; Sun, Zhongwei; Jiang, Lei
2008-08-04
We report a foaming-polymerization method to prepare stable polyaniline (PANI)/polyvinyl alcohol (PVA) foams. The formation mechanism of the foam materials is investigated and the photoelectric conversion properties of PANI/PVA foams are studied in detail. The enhancement of photoelectric conversion behavior in foams is achieved, which has potential application in solar cells and nano-electronics devices.
Chen, J.; Zhuang, G. Li, Q.; Liu, Y.; Gao, L.; Zhou, Y. N.; Jian, X.; Xiong, C. Y.; Wang, Z. J.; Brower, D. L.; Ding, W. X.
2014-11-15
A high-performance Faraday-effect polarimeter-interferometer system has been developed for the J-TEXT tokamak. This system has time response up to 1 μs, phase resolution < 0.1° and minimum spatial resolution ∼15 mm. High resolution permits investigation of fast equilibrium dynamics as well as magnetic and density perturbations associated with intrinsic Magneto-Hydro-Dynamic (MHD) instabilities and external coil-induced Resonant Magnetic Perturbations (RMP). The 3-wave technique, in which the line-integrated Faraday angle and electron density are measured simultaneously by three laser beams with specific polarizations and frequency offsets, is used. In order to achieve optimum resolution, three frequency-stabilized HCOOH lasers (694 GHz, >35 mW per cavity) and sensitive Planar Schottky Diode mixers are used, providing stable intermediate-frequency signals (0.5–3 MHz) with S/N > 50. The collinear R- and L-wave probe beams, which propagate through the plasma poloidal cross section (a = 0.25–0.27 m) vertically, are expanded using parabolic mirrors to cover the entire plasma column. Sources of systematic errors, e.g., stemming from mechanical vibration, beam non-collinearity, and beam polarization distortion are individually examined and minimized to ensure measurement accuracy. Simultaneous density and Faraday measurements have been successfully achieved for 14 chords. Based on measurements, temporal evolution of safety factor profile, current density profile, and electron density profile are resolved. Core magnetic and density perturbations associated with MHD tearing instabilities are clearly detected. Effects of non-axisymmetric 3D RMP in ohmically heated plasmas are directly observed by polarimetry for the first time.
Chen, J; Zhuang, G; Li, Q; Liu, Y; Gao, L; Zhou, Y N; Jian, X; Xiong, C Y; Wang, Z J; Brower, D L; Ding, W X
2014-11-01
A high-performance Faraday-effect polarimeter-interferometer system has been developed for the J-TEXT tokamak. This system has time response up to 1 μs, phase resolution < 0.1° and minimum spatial resolution ∼15 mm. High resolution permits investigation of fast equilibrium dynamics as well as magnetic and density perturbations associated with intrinsic Magneto-Hydro-Dynamic (MHD) instabilities and external coil-induced Resonant Magnetic Perturbations (RMP). The 3-wave technique, in which the line-integrated Faraday angle and electron density are measured simultaneously by three laser beams with specific polarizations and frequency offsets, is used. In order to achieve optimum resolution, three frequency-stabilized HCOOH lasers (694 GHz, >35 mW per cavity) and sensitive Planar Schottky Diode mixers are used, providing stable intermediate-frequency signals (0.5-3 MHz) with S/N > 50. The collinear R- and L-wave probe beams, which propagate through the plasma poloidal cross section (a = 0.25-0.27 m) vertically, are expanded using parabolic mirrors to cover the entire plasma column. Sources of systematic errors, e.g., stemming from mechanical vibration, beam non-collinearity, and beam polarization distortion are individually examined and minimized to ensure measurement accuracy. Simultaneous density and Faraday measurements have been successfully achieved for 14 chords. Based on measurements, temporal evolution of safety factor profile, current density profile, and electron density profile are resolved. Core magnetic and density perturbations associated with MHD tearing instabilities are clearly detected. Effects of non-axisymmetric 3D RMP in ohmically heated plasmas are directly observed by polarimetry for the first time.
Constructing stable 3D hydrodynamical models of giant stars
NASA Astrophysics Data System (ADS)
Ohlmann, Sebastian T.; Röpke, Friedrich K.; Pakmor, Rüdiger; Springel, Volker
2017-02-01
Hydrodynamical simulations of stellar interactions require stable models of stars as initial conditions. Such initial models, however, are difficult to construct for giant stars because of the wide range in spatial scales of the hydrostatic equilibrium and in dynamical timescales between the core and the envelope of the giant. They are needed for, e.g., modeling the common envelope phase where a giant envelope encompasses both the giant core and a companion star. Here, we present a new method of approximating and reconstructing giant profiles from a stellar evolution code to produce stable models for multi-dimensional hydrodynamical simulations. We determine typical stellar stratification profiles with the one-dimensional stellar evolution code mesa. After an appropriate mapping, hydrodynamical simulations are conducted using the moving-mesh code arepo. The giant profiles are approximated by replacing the core of the giant with a point mass and by constructing a suitable continuation of the profile to the center. Different reconstruction methods are tested that can specifically control the convective behaviour of the model. After mapping to a grid, a relaxation procedure that includes damping of spurious velocities yields stable models in three-dimensional hydrodynamical simulations. Initially convectively stable configurations lead to stable hydrodynamical models while for stratifications that are convectively unstable in the stellar evolution code, simulations recover the convective behaviour of the initial model and show large convective plumes with Mach numbers up to 0.8. Examples are shown for a 2 M⊙ red giant and a 0.67 M⊙ asymptotic giant branch star. A detailed analysis shows that the improved method reliably provides stable models of giant envelopes that can be used as initial conditions for subsequent hydrodynamical simulations of stellar interactions involving giant stars.
NASA Astrophysics Data System (ADS)
Lucia, Umberto
2016-02-01
The balance of forces and processes between the system and the environment and the processes inside the system are the result of the flows of the quanta. Moreover, the transition between two thermodynamic states is the consequence of absorption or emission of quanta, but, during the transition, the entropy variation due to the irreversibility occurs and it breaks any symmetry of time. Consequently, the irreversibility is the result of a transition, a process, an interaction between the system and its environment. This interaction results completely time-irreversible for any real process because of irreversibility. As a consequence, a proof of the third law is obtained proving that the zero temperature state can be achieved only for an infinite work lost for dissipation or in an infinite time. The fundamental role of time both in equilibrium and in non equilibrium analysis is pointed out. Moreover, the non equilibrium temperature is related to the entropy generation and its fluctuation rate; indeed, non-stationary temperature means that the system has not yet attained free energy minimum state, i.e., the maximum entropy state; the consequence is that the zero temperature state can be achieved only for an infinite work lost for dissipation or in an infinite time. In engineering thermodynamics the efficiency is always obtained without any consideration on time, while, here, just the time is introduced as a fundamental quantity of the analysis of non equilibrium states.
An Equilibrium and Kinetic Investigation of Salt-Cycloamylose Complexes
1976-12-08
Coneinut on reverse aide It necessary and identify by blo * number) Equilibrium constants inorganic anions Rate constants Ultrasonic relaxation Inclusion...The equilibrium constants and rate constants for the formation of inclusion complexes of cycloheptaamylose with small inorganic anions were measured by...of cyclo- amylose chemistry. Recently, equilibrium constants for cyclohexaamylose, sometimes denoted by a-CD, with various Tnorganic salts were
Hanging an Airplane: A Case Study in Static Equilibrium
ERIC Educational Resources Information Center
Katz, Debora M.
2009-01-01
Our classrooms are filled with engineering majors who take a semester-long course in static equilibrium. Many students find this class too challenging and drop their engineering major. In our introductory physics class, we often breeze through static equilibrium; to physicists equilibrium is just a special case of Newton's second law. While it is…
On the Chermnykh-Like Problems: II. The Equilibrium Points
NASA Astrophysics Data System (ADS)
Yeh, Li-Chin; Jiang, Ing-Guey
2006-12-01
Motivated by Papadakis (2005a, b), we study a Chermnykh-like problem, in which an additional gravitational potential from the belt is included. In addition to the usual five equilibrium points (three collinear and two triangular points), there are some new equilibrium points for this system. We studied the conditions for the existence of these new equilibrium points both analytically and numerically.
Investigating High School Students' Understanding of Chemical Equilibrium Concepts
ERIC Educational Resources Information Center
Karpudewan, Mageswary; Treagust, David F.; Mocerino, Mauro; Won, Mihye; Chandrasegaran, A. L.
2015-01-01
This study investigated the year 12 students' (N = 56) understanding of chemical equilibrium concepts after instruction using two conceptual tests, the "Chemical Equilibrium Conceptual Test 1" ("CECT-1") consisting of nine two-tier multiple-choice items and the "Chemical Equilibrium Conceptual Test 2"…
Towards breaking temperature equilibrium in multi-component Eulerian schemes
Grove, John W; Masser, Thomas
2009-01-01
We investigate the effects ofthermal equilibrium on hydrodynamic flows and describe models for breaking the assumption ofa single temperature for a mixture of components in a cell. A computational study comparing pressure-temperature equilibrium simulations of two dimensional implosions with explicit front tracking is described as well as implementation and J-D calculations for non-equilibrium temperature methods.
Acid Base Equilibrium in a Lipid/Water Gel
NASA Astrophysics Data System (ADS)
Streb, Kristina K.; Ilich, Predrag-Peter
2003-12-01
A new and original experiment in which partition of bromophenol blue dye between water and lipid/water gel causes a shift in the acid base equilibrium of the dye is described. The dye-absorbing material is a monoglyceride food additive of plant origin that mixes freely with water to form a stable cubic phase gel; the nascent gel absorbs the dye from aqueous solution and converts it to the acidic form. There are three concurrent processes taking place in the experiment: (a) formation of the lipid/water gel, (b) absorption of the dye by the gel, and (c) protonation of the dye in the lipid/water gel environment. As the aqueous solution of the dye is a deep purple-blue color at neutral pH and yellow at acidic pH the result of these processes is visually striking: the strongly green-yellow particles of lipid/water gel are suspended in purple-blue aqueous solution. The local acidity of the lipid/water gel is estimated by UV vis spectrophotometry. This experiment is an example of host-guest (lipid/water gel dye) interaction and is suitable for project-type biophysics, physical chemistry, or biochemistry labs. The experiment requires three, 3-hour lab sessions, two of which must not be separated by more than two days.
Ising Model Reprogramming of a Repeat Protein's Equilibrium Unfolding Pathway.
Millership, C; Phillips, J J; Main, E R G
2016-05-08
Repeat proteins are formed from units of 20-40 aa that stack together into quasi one-dimensional non-globular structures. This modular repetitive construction means that, unlike globular proteins, a repeat protein's equilibrium folding and thus thermodynamic stability can be analysed using linear Ising models. Typically, homozipper Ising models have been used. These treat the repeat protein as a series of identical interacting subunits (the repeated motifs) that couple together to form the folded protein. However, they cannot describe subunits of differing stabilities. Here we show that a more sophisticated heteropolymer Ising model can be constructed and fitted to two new helix deletion series of consensus tetratricopeptide repeat proteins (CTPRs). This analysis, showing an asymmetric spread of stability between helices within CTPR ensembles, coupled with the Ising model's predictive qualities was then used to guide reprogramming of the unfolding pathway of a variant CTPR protein. The designed behaviour was engineered by introducing destabilising mutations that increased the thermodynamic asymmetry within a CTPR ensemble. The asymmetry caused the terminal α-helix to thermodynamically uncouple from the rest of the protein and preferentially unfold. This produced a specific, highly populated stable intermediate with a putative dimerisation interface. As such it is the first step in designing repeat proteins with function regulated by a conformational switch.
Equilibrium contour of liquid bridges connected by pressure
NASA Astrophysics Data System (ADS)
Montanero, J. M.; Acero, F. J.; Gabezas, M. G.; Moya, J. M.
2002-12-01
The equilibria and stability in zero gravity of fixed boundary dual liquid bridges have been analyzed recently [B.J. Lowry, Phys. Fluids, vol. 12, p. 1005 (2000)]. Dual liquid bridges consist of two fixed-length sub-bridges connected by a free liquid passage so that the two sub-bridges are coupled by pressure. In the fixed pressure case, this fluid configuration is found to be more stable than a single bridge of equal length. This result lends a certain relevance to dual liquid bridges, especially in applications which involve pumping through capillaries. We here provide explicit formulas to predict the equilibrium contour of an arbitrary number of connected liquid bridges under microgravity conditions. The results are obtained for configurations close to cylindrical by using a perturbation expansion. The analytical predictions are compared with numerical data obtained by means of a finite difference scheme. The agreement is quite good for moderate axisymmetric and non-axisymmetric perturbations. Both analytical and numerical results are compared with experiments. The comparison confirms the validity of the theoretical approaches.
Equilibrium Strontium Isotope Fractionation in Minerals and Solution
NASA Astrophysics Data System (ADS)
Schauble, E. A.; Griffith, E. M.
2011-12-01
Recent interest in stable strontium isotope fractionation highlights our lack of understanding of the processes separating the isotopes of heavy elements in nature. Here we present thermodynamic calculations of equilibrium strontium isotope (88Sr/86Sr) fractionation in minerals and aqueous solution (by analogy to crystalline strontium hydrates). Strontium is among the ten most abundant dissolved ions seawater, and is unique in this group because it encompasses an extensively studied, long-lived radiogenic tracer (87Sr/86Sr) as well as three stable isotopes. Strontium is also widely distributed as a trace element in sedimentary minerals (especially carbonates and sulfates) and more broadly as a substituent for the major elements calcium, sodium and/or potassium in high-temperature igneous and metamorphic assemblages. However, we are aware of only a few theoretical or experimental studies of fractionation of strontium isotopes in crystals or solution (1). An important goal of our work is to provide a baseline for determining whether equilibrium isotope partitioning is important for generating observed signatures, which can be particularly difficult to establish experimentally in solid materials at ambient temperatures. Mass dependent fractionations are estimated for stoichiometric strontium-bearing crystals, including strontianite (SrCO3), celestine (SrSO4), strontia (SrO), and strontiofluorite (SrF2), as well as crystals with hydrated Sr2+-ions (e.g., SrCl2.6H2O, which contains a [Sr(H2O)9]2+ substructure) and strontium-substituted barite (Sr:BaSO4). Calculations are based on density functional perturbation theory models of the vibrational (phonon) densities of states of 86Sr- and 88Sr-substituted crystals. Most of the models of celestine indicate instability in the known orthorhombic structure - possibly because of shortcomings in pseudopotentials or density functionals. The models predict that fractionations between crystals tend to be small; strontia
Diffusion and thermodynamic equilibrium under pressure variations
NASA Astrophysics Data System (ADS)
Moulas, Evangelos; Tajčmanová, Lucie; Vrijmoed, Johannes; Podladchikov, Yuri
2015-04-01
Pressure is one of the most fundamental variables in mineral thermodynamics. In that respect, pressure-sensitive mineral reactions provide an important constraint on pressure under which the rock was developed. One implicit assumption when interpreting such pressure estimates is that the state-of-stress is close to hydrostatic, homogeneous and that the differential stress is negligible. Recent spectroscopic data from the mineral scale documenting pressure variations do not support this assumption. In addition to observations, mechanical models (numerical and analytical) suggest that rocks can develop and maintain heterogeneous pressure distributions at geological time scales. The recently developed unconventional barometry explains chemical zoning in minerals as a result of a pressure variation. We focus to apply the unconventional barometry in cases where chemical zoning in minerals cannot be explained by sluggish kinetics. In that respect, the unconventional barometry offers an alternative view of the chemical zoning which is consistent with thermodynamic equilibrium. However, to distinguish between a pressure-controlled chemical zoning and a zoning reflecting an incomplete chemical reaction is still challenging, especially for multicomponent systems. In this contribution, different types of chemical zoning are discussed. We investigate plagioclase rims around kyanite from an amphibolitized eclogite from Rhodope Metamorphic Complex (Greece-Bulgaria) as a case study and compare them with similar published textures from the Bohemian Massif. Mineral microstructures and phase equilibrium suggest that both rocks experienced near-isothermal decompression at high (>700C) temperatures. However, several distinct microstructural features suggest the development and/or the decay of mechanically maintained heterogeneous pressure distributions. We discuss our results and interpretations based on phase-equilibrium modeling, unconventional barometry and diffusion modeling under
Multicomponent Equilibrium Models for Testing Geothermometry Approaches
Cooper, D. Craig; Palmer, Carl D.; Smith, Robert W.; McLing, Travis L.
2013-02-01
Geothermometry is an important tool for estimating deep reservoir temperature from the geochemical composition of shallower and cooler waters. The underlying assumption of geothermometry is that the waters collected from shallow wells and seeps maintain a chemical signature that reflects equilibrium in the deeper reservoir. Many of the geothermometers used in practice are based on correlation between water temperatures and composition or using thermodynamic calculations based a subset (typically silica, cations or cation ratios) of the dissolved constituents. An alternative approach is to use complete water compositions and equilibrium geochemical modeling to calculate the degree of disequilibrium (saturation index) for large number of potential reservoir minerals as a function of temperature. We have constructed several “forward” geochemical models using The Geochemist’s Workbench to simulate the change in chemical composition of reservoir fluids as they migrate toward the surface. These models explicitly account for the formation (mass and composition) of a steam phase and equilibrium partitioning of volatile components (e.g., CO2, H2S, and H2) into the steam as a result of pressure decreases associated with upward fluid migration from depth. We use the synthetic data generated from these simulations to determine the advantages and limitations of various geothermometry and optimization approaches for estimating the likely conditions (e.g., temperature, pCO2) to which the water was exposed in the deep subsurface. We demonstrate the magnitude of errors that can result from boiling, loss of volatiles, and analytical error from sampling and instrumental analysis. The estimated reservoir temperatures for these scenarios are also compared to conventional geothermometers. These results can help improve estimation of geothermal resource temperature during exploration and early development.
Thermo-chemical dynamics and chemical quasi-equilibrium of plasmas in thermal non-equilibrium
NASA Astrophysics Data System (ADS)
Massot, Marc; Graille, Benjamin; Magin, Thierry E.
2011-05-01
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.
Modeling Equilibrium of microRNA Expression
Chan, Lawrence W. C.
2011-01-01
MicroRNAs are a class of non-coding RNAs and the dysregulated expression of these short RNA molecules was frequently observed in cancer cells. The steady state level of microRNA concentration may differentiate the biological function of the cells between normal and impaired. To understand the steady state or equilibrium of microRNAs, their interactions with transcription factors and target genes need to be explored and visualized through prediction and network analysis algorithms. This article discusses the application of mathematical model for simulating the dynamics of network feedback loop so as to decipher the mechanism of microRNA regulation. PMID:22303331
Process for operating equilibrium controlled reactions
Nataraj, Shankar; Carvill, Brian Thomas; Hufton, Jeffrey Raymond; Mayorga, Steven Gerard; Gaffney, Thomas Richard; Brzozowski, Jeffrey Richard
2001-01-01
A cyclic process for operating an equilibrium controlled reaction in a plurality of reactors containing an admixture of an adsorbent and a reaction catalyst suitable for performing the desired reaction which is operated in a predetermined timed sequence wherein the heating and cooling requirements in a moving reaction mass transfer zone within each reactor are provided by indirect heat exchange with a fluid capable of phase change at temperatures maintained in each reactor during sorpreaction, depressurization, purging and pressurization steps during each process cycle.
Microscopic theory of equilibrium polariton condensates
NASA Astrophysics Data System (ADS)
Xue, Fei; Wu, Fengcheng; Xie, Ming; Su, Jung-Jung; MacDonald, A. H.
2016-12-01
We present a microscopic theory of the equilibrium polariton condensate state of a semiconductor quantum well in a planar optical cavity. The theory accounts for the adjustment of matter excitations to the presence of a coherent photon field, predicts effective polariton-polariton interaction strengths that are weaker and condensate exciton fractions that are smaller than in the commonly employed exciton-photon model, and yields effective Rabi coupling strengths that depend on the detuning of the cavity-photon energy relative to the bare exciton energy. The dressed quasiparticle bands that appear naturally in the theory provide a mechanism for electrical manipulation of polariton condensates.
NASA Astrophysics Data System (ADS)
Capuzzi, P.; Hernández, E. S.; Szybisz, L.
2008-10-01
We present a generalization of the fluid-dynamical scheme developed for nuclear physics to the case of two trapped fermion species with pairing interactions. To establish a macroscopic description of the mass and momentum conservation laws, we adopt a generalization of the usual Thomas-Fermi approach that includes the pairing energy. We analyze the equilibrium density and gap profiles for an equal population mixture of harmonically trapped Li6 atoms for different choices of the local equation of state. We examine slight departures from equilibrium within our formulation, finding that density oscillations can propagate as first sound coupled to pairing vibrations, that in a homogeneous fermion system exhibit a Bogoliubov-like quasiparticle spectrum. In this case, the dispersion relation for the coupled modes displays a rich scenario of stable, unstable, and damped regimes.
Tellurium Stable Isotope Fractionation in Chondritic Meteorites
NASA Astrophysics Data System (ADS)
Fehr, M. A.; Hammond, S. J.; Parkinson, I. J.
2014-09-01
New Te double spike procedures were set up to obtain high-precision accurate Te stable isotope data. Tellurium stable isotope data for 16 chondrite falls are presented, providing evidence for significant Te stable isotope fractionation.
Bradburne, John; Patton, Tisha C.
2001-02-25
When Fluor Fernald took over the management of the Fernald Environmental Management Project in 1992, the estimated closure date of the site was more than 25 years into the future. Fluor Fernald, in conjunction with DOE-Fernald, introduced the Accelerated Cleanup Plan, which was designed to substantially shorten that schedule and save taxpayers more than $3 billion. The management of Fluor Fernald believes there are three fundamental concerns that must be addressed by any contractor hoping to achieve closure of a site within the DOE complex. They are relationship management, resource management and contract management. Relationship management refers to the interaction between the site and local residents, regulators, union leadership, the workforce at large, the media, and any other interested stakeholder groups. Resource management is of course related to the effective administration of the site knowledge base and the skills of the workforce, the attraction and retention of qualified a nd competent technical personnel, and the best recognition and use of appropriate new technologies. Perhaps most importantly, resource management must also include a plan for survival in a flat-funding environment. Lastly, creative and disciplined contract management will be essential to effecting the closure of any DOE site. Fluor Fernald, together with DOE-Fernald, is breaking new ground in the closure arena, and ''business as usual'' has become a thing of the past. How Fluor Fernald has managed its work at the site over the last eight years, and how it will manage the new site closure contract in the future, will be an integral part of achieving successful closure at Fernald.
Bayesian stable isotope mixing models
In this paper we review recent advances in Stable Isotope Mixing Models (SIMMs) and place them into an over-arching Bayesian statistical framework which allows for several useful extensions. SIMMs are used to quantify the proportional contributions of various sources to a mixtur...
Synthesis of thermally stable polymers
NASA Technical Reports Server (NTRS)
Butler, G. B.
1978-01-01
The reaction of bis triazo linediones with divinyl esters and substituted styrenes was investigated. Twenty new polymers were derived via reaction of two previously synthesized bis triazol linediones and four new bis atriazol linediones with eight styrenes. The structure and polymer properties of these thermally stable polymers was examined. The reaction of triazo linediones with enol esters was also considered.
A computer simulation using spreadsheets for learning concept of steady-state equilibrium
NASA Astrophysics Data System (ADS)
Sharda, Vandana; Sastri, O. S. K. S.; Bhardwaj, Jyoti; Jha, Arbind K.
2016-03-01
In this paper, we present a simple spreadsheet based simulation activity that can be performed by students at the undergraduate level. This simulation is implemented in free open source software (FOSS) LibreOffice Calc, which is available for both Windows and Linux platform. This activity aims at building the probability distribution for the possible macro-states of a system. This has been achieved by randomly sampling the configuration space consisting of all the possible microstates and determining the corresponding macrostate for each of the samples, which is akin to Monte-Carlo simulation. This simulation could act as a very useful tool in engaging students for learning the concepts of microstates, macrostates and steady state equilibrium, once the ideas have been introduced in the classroom. Further, the effect of the number of particles on the quality of steady state equilibrium achieved demonstrates the idea of thermodynamic limit.
Kimura, Yasuyuki; Siméon, Fabrice G; Zoghbi, Sami S; Zhang, Yi; Hatazawa, Jun; Pike, Victor W; Innis, Robert B; Fujita, Masahiro
2012-02-01
A new PET ligand, 3-fluoro-5-(2-(2-(18)F-(fluoromethyl)-thiazol-4-yl)ethynyl)benzonitrile (18F-SP203) can quantify metabotropic glutamate subtype 5 receptors (mGluR5) in human brain by a bolus injection and kinetic modeling. As an alternative approach to a bolus injection, binding can simply be measured as a ratio of tissue to metabolite-corrected plasma at a single time point under equilibrium conditions achieved by administering the radioligand with a bolus injection followed by a constant infusion. The purpose of this study was to validate the equilibrium method as an alternative to the standard kinetic method for measuring 18F-SP203 binding in the brain. Nine healthy subjects were injected with 18F-SP203 using a bolus plus constant infusion for 300 min. A single ratio of bolus-to-constant infusion (the activity of bolus equaled to that of infusion over 219 min) was applied to all subjects to achieve equilibrium in approximately 120 min. As a measure of ligand binding, we compared total distribution volume (VT) calculated by the equilibrium and kinetic methods in each scan. The equilibrium method calculated VT by the ratio of radioactivity in the brain to the concentration of 18F-SP203 in arterial plasma at 120 min, and the kinetic method calculated VT by a two-tissue compartment model using brain and plasma dynamic data from 0 to 120 min. VT obtained via the equilibrium method was highly correlated with VT obtained via kinetic modeling. Inter-subject variability of VT obtained via the equilibrium method was slightly smaller than VT obtained via the kinetic method. VT obtained via the equilibrium method was ~10% higher than VT obtained via the kinetic method, indicating a small difference between the measurements. Taken together, the results of this study show that using the equilibrium method is an acceptable alternative to the standard kinetic method when using 18F-SP203 to measure mGluR5. Although small differences in the measurements obtained via the
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 capacity with probit-based stochastic user equilibrium problem
Lu, Lili; Wang, Jian; Zheng, Pengjun; Wang, Wei
2017-01-01
Among different stochastic user equilibrium (SUE) traffic assignment models, the Logit-based stochastic user equilibrium (SUE) is extensively investigated by researchers. It is constantly formulated as the low-level problem to describe the drivers’ route choice behavior in bi-level problems such as network design, toll optimization et al. The Probit-based SUE model receives far less attention compared with Logit-based model albeit the assignment result is more consistent with drivers’ behavior. It is well-known that due to the identical and irrelevant alternative (IIA) assumption, the Logit-based SUE model is incapable to deal with route overlapping problem and cannot account for perception variance with respect to trips. This paper aims to explore the network capacity with Probit-based traffic assignment model and investigate the differences of it is with Logit-based SUE traffic assignment models. The network capacity is formulated as a bi-level programming where the up-level program is to maximize the network capacity through optimizing input parameters (O-D multiplies and signal splits) while the low-level program is the Logit-based or Probit-based SUE problem formulated to model the drivers’ route choice. A heuristic algorithm based on sensitivity analysis of SUE problem is detailed presented to solve the proposed bi-level program. Three numerical example networks are used to discuss the differences of network capacity between Logit-based SUE constraint and Probit-based SUE constraint. This study finds that while the network capacity show different results between Probit-based SUE and Logit-based SUE constraints, the variation pattern of network capacity with respect to increased level of travelers’ information for general network under the two type of SUE problems is the same, and with certain level of travelers’ information, both of them can achieve the same maximum network capacity. PMID:28178284
Equilibrium model constraints on baryon cycling across cosmic time
NASA Astrophysics Data System (ADS)
Mitra, Sourav; Davé, Romeel; Finlator, Kristian
2015-09-01
Galaxies strongly self-regulate their growth via energetic feedback from stars, supernovae, and black holes, but these processes are among the least understood aspects of galaxy formation theory. We present an analytic galaxy evolution model that directly constrains such feedback processes from observed galaxy scaling relations. The equilibrium model, which is broadly valid for star-forming central galaxies that dominate cosmic star formation, is based on the ansatz that galaxies live in a slowly evolving equilibrium between inflows, outflows, and star formation. Using a Bayesian Monte Carlo Markov chain approach, we constrain our model to match observed galaxy scaling relations between stellar mass and halo mass, star formation rate, and metallicity from 0 < z < 2. A good fit (χ2 ≈ 1.6) is achieved with eight free parameters. We further show that constraining our model to any two of the three data sets also produces a fit to the third that is within reasonable systematic uncertainties. The resulting best-fitting parameters that describe baryon cycling suggest galactic outflow scalings intermediate between energy and momentum-driven winds, a weak dependence of wind recycling time on mass, and a quenching mass scale that evolves modestly upwards with redshift. This model further predicts a stellar mass-star formation rate relation that is in good agreement with observations to z ˜ 6. Our results suggest that this simple analytic framework captures the basic physical processes required to model the mean evolution of stars and metals in galaxies, despite not incorporating many canonical ingredients of galaxy formation models such as merging or disc formation.
In command of non-equilibrium.
Roduner, Emil; Radhakrishnan, Shankara Gayathri
2016-05-21
The second law of thermodynamics is well known for determining the direction of spontaneous processes in the laboratory, life and the universe. It is therefore often called the arrow of time. Less often discussed but just as important is the effect of kinetic barriers which intercept equilibration and preserve highly ordered, high energy non-equilibrium states. Examples of such states are many modern materials produced intentionally for technological applications. Furthermore, all living organisms fuelled directly by photosynthesis and those fuelled indirectly by living on high energy nutrition represent preserved non-equilibrium states. The formation of these states represents the local reversal of the arrow of time which only seemingly violates the second law. It has been known since the seminal work of Prigogine that the stabilisation of these states inevitably requires the dissipation of energy in the form of waste heat. It is this feature of waste heat dissipation following the input of energy that drives all processes occurring at a non-zero rate. Photosynthesis, replication of living organisms, self-assembly, crystal shape engineering and distillation have this principle in common with the well-known Carnot cycle in the heat engine. Drawing on this analogy, we subsume these essential and often sophisticated driven processes under the term machinery of life.
Equilibrium stellar systems with spindle singularities
NASA Technical Reports Server (NTRS)
Shapiro, Stuart L.; Teukolsky, Saul A.
1992-01-01
Equilibrium sequences of axisymmetric Newtonian clusters that tend toward singular states are constructed. The distribution functions are chosen to be of the form f = f(E, Jz). The numerical method then determines the density and gravitational potential self-consistently to satisfy Poisson's equation. For the prolate models, spindle singularities arise from the depletion of angular momentum near the symmetry axis. While the resulting density enhancement is confined to the region near the axis, the influence of the spindle extends much further out through its tidal gravitational field. Centrally condensed prolate clusters may contain strong-field regions even though the spindle mass is small and the mean cluster eccentricity is not extreme. While the calculations performed here are entirely Newtonian, the issue of singularities is an important topic in general relativity. Equilibrium solutions for relativistic star clusters can provide a testing ground for exploring this issue. The methods used in this paper for building nonspherical clusters can be extended to relativistic systems.
Symmetries in fluctuations far from equilibrium.
Hurtado, Pablo I; Pérez-Espigares, Carlos; del Pozo, Jesús J; Garrido, Pedro L
2011-05-10
Fluctuations arise universally in nature as a reflection of the discrete microscopic world at the macroscopic level. Despite their apparent noisy origin, fluctuations encode fundamental aspects of the physics of the system at hand, crucial to understand irreversibility and nonequilibrium behavior. To sustain a given fluctuation, a system traverses a precise optimal path in phase space. Here we show that by demanding invariance of optimal paths under symmetry transformations, new and general fluctuation relations valid arbitrarily far from equilibrium are unveiled. This opens an unexplored route toward a deeper understanding of nonequilibrium physics by bringing symmetry principles to the realm of fluctuations. We illustrate this concept studying symmetries of the current distribution out of equilibrium. In particular we derive an isometric fluctuation relation that links in a strikingly simple manner the probabilities of any pair of isometric current fluctuations. This relation, which results from the time-reversibility of the dynamics, includes as a particular instance the Gallavotti-Cohen fluctuation theorem in this context but adds a completely new perspective on the high level of symmetry imposed by time-reversibility on the statistics of nonequilibrium fluctuations. The new symmetry implies remarkable hierarchies of equations for the current cumulants and the nonlinear response coefficients, going far beyond Onsager's reciprocity relations and Green-Kubo formulas. We confirm the validity of the new symmetry relation in extensive numerical simulations, and suggest that the idea of symmetry in fluctuations as invariance of optimal paths has far-reaching consequences in diverse fields.
Symmetries in fluctuations far from equilibrium
Hurtado, Pablo I.; Pérez-Espigares, Carlos; del Pozo, Jesús J.; Garrido, Pedro L.
2011-01-01
Fluctuations arise universally in nature as a reflection of the discrete microscopic world at the macroscopic level. Despite their apparent noisy origin, fluctuations encode fundamental aspects of the physics of the system at hand, crucial to understand irreversibility and nonequilibrium behavior. To sustain a given fluctuation, a system traverses a precise optimal path in phase space. Here we show that by demanding invariance of optimal paths under symmetry transformations, new and general fluctuation relations valid arbitrarily far from equilibrium are unveiled. This opens an unexplored route toward a deeper understanding of nonequilibrium physics by bringing symmetry principles to the realm of fluctuations. We illustrate this concept studying symmetries of the current distribution out of equilibrium. In particular we derive an isometric fluctuation relation that links in a strikingly simple manner the probabilities of any pair of isometric current fluctuations. This relation, which results from the time-reversibility of the dynamics, includes as a particular instance the Gallavotti–Cohen fluctuation theorem in this context but adds a completely new perspective on the high level of symmetry imposed by time-reversibility on the statistics of nonequilibrium fluctuations. The new symmetry implies remarkable hierarchies of equations for the current cumulants and the nonlinear response coefficients, going far beyond Onsager’s reciprocity relations and Green–Kubo formulas. We confirm the validity of the new symmetry relation in extensive numerical simulations, and suggest that the idea of symmetry in fluctuations as invariance of optimal paths has far-reaching consequences in diverse fields. PMID:21493865
Non-equilibrium modelling of transferred arcs
NASA Astrophysics Data System (ADS)
Haidar, J.
1999-02-01
A two-temperature, variable-density, arc model has been developed for description of high-current free-burning arcs, including departures from thermodynamic and chemical equilibrium in the plasma. The treatment includes the arc, the anode and the cathode and considers the separate energy balance of the electrons and the heavy particles, together with the continuity equations for these species throughout the plasma. The output includes a two-dimensional distribution for the temperatures and densities both of the electrons and of the heavy particles, plasma velocity, current density and electrical potential throughout the arc. For a 200 A arc in pure argon at 1 atm, we calculate large differences between the temperatures of the electrons and the heavy particles in the plasma region near the cathode tip, together with large departures from local chemical plasma equilibrium. In the main body of the arc at high plasma temperatures, we predict minor differences between the temperatures of the electrons and the heavy particles, which are inconsistent with recent measurements using laser-scattering techniques showing differences of up to several thousand degrees. However, we find that, for the region in front of the cathode tip, the ground-state level of the neutral atoms is overpopulated relative to the corresponding populations under conditions of LTE, in agreement with experimental observations. These departures from LTE are caused by the injection of a large mass flow of cold gas into the arc core due to arc constriction at the tip of the cathode.
Accurate equilibrium structures for piperidine and cyclohexane.
Demaison, Jean; Craig, Norman C; Groner, Peter; Écija, Patricia; Cocinero, Emilio J; Lesarri, Alberto; Rudolph, Heinz Dieter
2015-03-05
Extended and improved microwave (MW) measurements are reported for the isotopologues of piperidine. New ground state (GS) rotational constants are fitted to MW transitions with quartic centrifugal distortion constants taken from ab initio calculations. Predicate values for the geometric parameters of piperidine and cyclohexane are found from a high level of ab initio theory including adjustments for basis set dependence and for correlation of the core electrons. Equilibrium rotational constants are obtained from GS rotational constants corrected for vibration-rotation interactions and electronic contributions. Equilibrium structures for piperidine and cyclohexane are fitted by the mixed estimation method. In this method, structural parameters are fitted concurrently to predicate parameters (with appropriate uncertainties) and moments of inertia (with uncertainties). The new structures are regarded as being accurate to 0.001 Å and 0.2°. Comparisons are made between bond parameters in equatorial piperidine and cyclohexane. Another interesting result of this study is that a structure determination is an effective way to check the accuracy of the ground state experimental rotational constants.
Non-equilibrium many body dynamics
Creutz, M.; Gyulassy, M.
1997-09-22
This Riken BNL Research Center Symposium on Non-Equilibrium Many Body Physics was held on September 23-25, 1997 as part of the official opening ceremony of the Center at Brookhaven National Lab. A major objective of theoretical work at the center is to elaborate on the full spectrum of strong interaction physics based on QCD, including the physics of confinement and chiral symmetry breaking, the parton structure of hadrons and nuclei, and the phenomenology of ultra-relativistic nuclear collisions related to the up-coming experiments at RHIC. The opportunities and challenges of nuclear and particle physics in this area naturally involve aspects of the many body problem common to many other fields. The aim of this symposium was to find common theoretical threads in the area of non-equilibrium physics and modern transport theories. The program consisted of invited talks on a variety topics from the fields of atomic, condensed matter, plasma, astrophysics, cosmology, and chemistry, in addition to nuclear and particle physics. Separate abstracts have been indexed into the database for contributions to this workshop.
Turbulence modeling for non-equilibrium flow
NASA Technical Reports Server (NTRS)
Durbin, P. A.
1995-01-01
The work performed during this year has involved further assessment and extension of the k-epsilon-v(exp 2) model, and initiation of work on scalar transport. The latter is introduced by the contribution of Y. Shabany to this volume. Flexible, computationally tractable models are needed for engineering CFD. As computational technology has progressed, the ability and need to use elaborate turbulence closure models has increased. The objective of our work is to explore and develop new analytical frameworks that might extend the applicability of the modeling techniques. In past years the development of a method for near-wall modeling was described. The method has been implemented into a CFD code and its viability has been demonstrated by various test cases. Further tests are reported herein. Non-equilibrium near-wall models are needed for some heat transfer applications. Scalar transport seems generally to be more sensitive to non-equilibrium effects than is momentum transport. For some applications turbulence anisotropy plays a role and an estimate of the full Reynolds stress tensor is needed. We have begun work on scalar transport per se, but in this brief I will only report on an extension of the k-epsilon-v(exp 2) model to predict the Reynolds stress tensor.
PROCEDURES FOR THE DERIVATION OF EQUILIBRIUM ...
This equilibrium partitioning sediment benchmark (ESB) document describes procedures to derive concentrations for 32 nonionic organic chemicals in sediment which are protective of the presence of freshwater and marine benthic organisms. The equilibrium partitioning (EqP) approach was chosen because it accounts for the varying biological availability of chemicals in different sediments and allows for the incorporation of the appropriate biological effects concentration. This provides for the derivation of benchmarks that are causally linked to the specific chemical, applicable across sediments, and appropriately protective of benthic organisms. EqP can be used to calculate ESBs for any toxicity endpoint for which there are water-only toxicity data; it is not limited to any single effect endpoint. For the purposes of this document, ESBs for 32 nonionic organic chemicals, including several low molecular weight aliphatic and aromatic compounds, pesticides, and phthalates, were derived using Final Chronic Values (FCV) from Water Quality Criteria (WQC) or Secondary Chronic Values (SCV) derived from existing toxicological data using the Great Lakes Water Quality Initiative (GLI) or narcosis theory approaches. These values are intended to be the concentration of each chemical in water that is protective of the presence of aquatic life. For nonionic organic chemicals demonstrating a narcotic mode of action, ESBs derived using the GLI approach specifically for fres
Structural design using equilibrium programming formulations
NASA Technical Reports Server (NTRS)
Scotti, Stephen J.
1995-01-01
Solutions to increasingly larger structural optimization problems are desired. However, computational resources are strained to meet this need. New methods will be required to solve increasingly larger problems. The present approaches to solving large-scale problems involve approximations for the constraints of structural optimization problems and/or decomposition of the problem into multiple subproblems that can be solved in parallel. An area of game theory, equilibrium programming (also known as noncooperative game theory), can be used to unify these existing approaches from a theoretical point of view (considering the existence and optimality of solutions), and be used as a framework for the development of new methods for solving large-scale optimization problems. Equilibrium programming theory is described, and existing design techniques such as fully stressed design and constraint approximations are shown to fit within its framework. Two new structural design formulations are also derived. The first new formulation is another approximation technique which is a general updating scheme for the sensitivity derivatives of design constraints. The second new formulation uses a substructure-based decomposition of the structure for analysis and sensitivity calculations. Significant computational benefits of the new formulations compared with a conventional method are demonstrated.
Entanglement equilibrium for higher order gravity
NASA Astrophysics Data System (ADS)
Bueno, Pablo; Min, Vincent S.; Speranza, Antony J.; Visser, Manus R.
2017-02-01
We show that the linearized higher derivative gravitational field equations are equivalent to an equilibrium condition on the entanglement entropy of small spherical regions in vacuum. This extends Jacobson's recent derivation of the Einstein equation using entanglement to include general higher derivative corrections. The corrections are naturally associated with the subleading divergences in the entanglement entropy, which take the form of a Wald entropy evaluated on the entangling surface. Variations of this Wald entropy are related to the field equations through an identity for causal diamonds in maximally symmetric spacetimes, which we derive for arbitrary higher derivative theories. If the variations are taken holding fixed a geometric functional that we call the generalized volume, the identity becomes an equivalence between the linearized constraints and the entanglement equilibrium condition. We note that the fully nonlinear higher curvature equations cannot be derived from the linearized equations applied to small balls, in contrast to the situation encountered in Einstein gravity. The generalized volume is a novel result of this work, and we speculate on its thermodynamic role in the first law of causal diamond mechanics, as well as its possible application to holographic complexity.
On statistical equilibrium in helical fluid flows
NASA Astrophysics Data System (ADS)
Kurgansky, M. V.
2006-06-01
The statistical mechanics of 3-D helical flows is re-examined for a continuum truncated at a top wavenumber. Based on the principle of equipartition of the flow enstrophy between helical modes, the emerging (i) energy spectrum law "-2" and (ii) formal mathematical analogy between the helicity and the thermodynamic entropy are discussed. It is noted that the "-2" scaling law is consistent with both spectral equilibrium and spectral cascade paradigms. In an attempt to apply the obtained results to a turbulent flow regime within the Earth's outer liquid core, where the net helicity of a turbulent flow component is presumably explained by Earth's rotation, it has been noticed that it is the energy spectral law "-1", but not "-2", which is likely realized there and within the logarithmic accuracy corresponds to the case of the velocity structure function [u(l)]2 independency on the spatial scale l, the latter is consistent with observations. It is argued that the "-1" scaling law can also be interpreted in terms of the spectral equilibrium and it is emphasized that the causes of the likely dominance of the spectral law "-1" over the spectral law "-2" in this geophysical application deserve further investigation and clarification.
Gyrokinetic Statistical Absolute Equilibrium and Turbulence
Jian-Zhou Zhu and Gregory W. Hammett
2011-01-10
A paradigm based on the absolute equilibrium of Galerkin-truncated inviscid systems to aid in understanding turbulence [T.-D. Lee, "On some statistical properties of hydrodynamical and magnetohydrodynamical fields," Q. Appl. Math. 10, 69 (1952)] is taken to study gyrokinetic plasma turbulence: A finite set of Fourier modes of the collisionless gyrokinetic equations are kept and the statistical equilibria are calculated; possible implications for plasma turbulence in various situations are discussed. For the case of two spatial and one velocity dimension, in the calculation with discretization also of velocity v with N grid points (where N + 1 quantities are conserved, corresponding to an energy invariant and N entropy-related invariants), the negative temperature states, corresponding to the condensation of the generalized energy into the lowest modes, are found. This indicates a generic feature of inverse energy cascade. Comparisons are made with some classical results, such as those of Charney-Hasegawa-Mima in the cold-ion limit. There is a universal shape for statistical equilibrium of gyrokinetics in three spatial and two velocity dimensions with just one conserved quantity. Possible physical relevance to turbulence, such as ITG zonal flows, and to a critical balance hypothesis are also discussed.
Ultra-stable oscillator with complementary transistors
NASA Technical Reports Server (NTRS)
Kleinberg, L. L. (Inventor)
1974-01-01
A high frequency oscillator, having both good short and long term stability, is formed by including a piezoelectric crystal in the base circuit of a first bi-polar transistor circuit, the bi-polar transistor itself operated below its transitional frequency and having its emitter load chosen so that the input impedance, looking into the base thereof, exhibits a negative resistance in parallel with a capacitive reactance. Combined with this basic circuit is an auxiliary, complementary, second bi-polar transistor circuit of the same form with the piezoelectric crystal being common to both circuits. By this configuration small changes in quiescent current are substantially cancelled by opposite variations in the second bi-polar transistor circuit, thereby achieving from the oscillator a signal having its frequency of oscillation stable over long time periods as well as short time periods.
Thermally Stable, Latent Olefin Metathesis Catalysts
Thomas, Renee M.; Fedorov, Alexey; Keitz, Benjamin K.
2011-01-01
Highly thermally stable N-aryl,N-alkyl N-heterocyclic carbene (NHC) ruthenium catalysts were designed and synthesized for latent olefin metathesis. These catalysts showed excellent latent behavior toward metathesis reactions, whereby the complexes were inactive at ambient temperature and initiated at elevated temperatures, a challenging property to achieve with second generation catalysts. A sterically hindered N-tert-butyl substituent on the NHC ligand of the ruthenium complex was found to induce latent behavior toward cross-metathesis reactions, and exchange of the chloride ligands for iodide ligands was necessary to attain latent behavior during ring-opening metathesis polymerization (ROMP). Iodide-based catalysts showed no reactivity toward ROMP of norbornene-derived monomers at 25 °C, and upon heating to 85 °C gave complete conversion of monomer to polymer in less than 2 hours. All of the complexes were very stable to air, moisture, and elevated temperatures up to at least 90 °C, and exhibited a long catalyst lifetime in solution at elevated temperatures. PMID:22282652
Helali, H.; Bchir, T.; Araoud, Z.; Charrada, K.
2013-04-15
The aim of this work is to study the local thermodynamic equilibrium (LTE) deviations in arc discharges plasma generated in high-intensity discharge lamps operating under an ac (50 Hz) power supply. To achieve this goal, we elaborate a two-temperature, two-dimensional, and time-depending model. We have found numerical results almost reproducing the experimental data, which allows us to validate this model. After validation, we have discussed different energy term effects on the LTE deviations.
Achievement Goals and Achievement Emotions: A Meta-Analysis
ERIC Educational Resources Information Center
Huang, Chiungjung
2011-01-01
This meta-analysis synthesized 93 independent samples (N = 30,003) in 77 studies that reported in 78 articles examining correlations between achievement goals and achievement emotions. Achievement goals were meaningfully associated with different achievement emotions. The correlations of mastery and mastery approach goals with positive achievement…
Stable light isotope biogeochemistry of hydrothermal systems.
Des Marais, D J
1996-01-01
The stable isotopic composition of the elements O, H, S and C in minerals and other chemical species can indicate the existence, extent, conditions and the processes (including biological activity) of hydrothermal systems. Hydrothermal alteration of the 18O/16O and D/H values of minerals can be used to detect fossil systems and delineate their areal extent. Water-rock interactions create isotopic signatures which indicate fluid composition, temperature, water-rock ratios, etc. The 18O/16O values of silica and carbonate deposits tend to increase with declining temperature and thus help to map thermal gradients. Measurements of D/H values can help to decipher the origin(s) of hydrothermal fluids. The 34S/32S and 13C/12C values of fluids and minerals reflect the origin of the S and C as well as oxygen fugacities and key redox processes. For example, a wide range of 34S/32S values which are consistent with equilibration below 100 degrees C between sulfide and sulfate can be attributed to sulfur metabolizing bacteria. Depending on its magnitude, the difference in the 13C/12C value of CO2 and carbonates versus organic carbon might be attributed either to equilibrium at hydrothermal temperatures or, if the difference exceeds 1% (10/1000), to organic biosynthesis. Along the thermal gradients of thermal spring outflows, the 13C/12C value of carbonates and 13C-depleted microbial organic carbon increases, principally due to the outgassing of relatively 13C-depleted CO2.
Universality in equilibrium and away from it: A personal perspective
Munoz, Miguel A.
2011-03-24
In this talk/paper I discuss the concept of universality in phase transitions and the question of whether universality classes are more robust in equilibrium than away from it. In both of these situations, the main ingredients determining universality are symmetries, conservation laws, the dimension of the space and of the order-parameter and the presence of long-range interactions or quenched disorder. The existence of detailed-balance and fluctuation-dissipation theorems imposes severe constraints on equilibrium systems, allowing to define universality classes in a very robust way; instead, non-equilibrium allows for more variability. Still, quite robust non-equilibrium universality classes have been identified in the last decades. Here, I discuss some examples in which (i) non-equilibrium phase transitions are simply controlled by equilibrium critical points, i.e. non-equilibrium ingredients turn out to be irrelevant in the renormalization group sense and (ii) non-equilibrium situations in which equilibrium seems to come out of the blue, generating an adequate effective description of intrinsically non-equilibrium problems. Afterwards, I shall describe different genuinely non-equilibrium phase transitions in which introducing small, apparently innocuous changes (namely: presence or absence of an underlying lattice, parity conservation in the overall number of particles, existence of an un-accessible vacuum state, deterministic versus stochastic microscopic rules, presence or absence of a Fermionic constraint), the critical behavior is altered, making the case for lack of robustness. However, it will be argued that in all these examples, there is an underlying good reason (in terms of general principles) for universality to be altered. The final conclusions are that: (i) robust universality classes exist both in equilibrium and non-equilibrium; (ii) symmetry and conservation principles are crucial in both, (iii) non-equilibrium allows for more variability (i
NASA Astrophysics Data System (ADS)
Sarangapani, Prasad; Hudson, Steven; Pathak, Jai; Migler, Kalman
2013-03-01
Equilibrium and non-equilibrium clustering are ubiquitous phenomena in soft matter physics and are typically observed in systems ranging from colloidal suspensions to monoclonal antibodies (mAbs). Such phenomena are central to understanding and preventing irreversible aggregation in addition to controlling viscosity challenges related to formulation and drug delivery of protein therapeutics. Curiously, little work has been done in exploring the cluster size dependence of low-shear viscosity and intrinsic viscosity in protein solutions in a controlled manner. In this work, we carefully control cluster size of reversible and irreversible clusters formed by globular proteins or monoclonal antibodies over a concentration range of 2 mg/mL-500 mg/mL and pH from 3-9. We find a marked dependence of low-shear viscosity on cluster size using custom-designed silicon-based microfluidic viscometers. Measurements of cluster sizes using static light scattering reveal a correlation of low shear viscosity as well as intrinsic viscosity with the average cluster size. We model the composition dependence of viscosity for the case of equilibrium and non-equilibrium clusters using an adaptation of a model recently presented by Minton for protein mixtures.
Technology Transfer Automated Retrieval System (TEKTRAN)
The distribution coefficient (KD) for the human drug carbamazepine was measured using a non-equilibrium technique. Repacked soil columns were prepared using an Airport silt loam (Typic Natrustalf) with an average organic matter content of 2.45%. Carbamazepine solutions were then leached through th...
NASA Technical Reports Server (NTRS)
Harm, D. L.; Taylor, L. C.
2006-01-01
Virtual environments offer unique training opportunities, particularly for training astronauts and preadapting them to the novel sensory conditions of microgravity. Two unresolved human factors issues in virtual reality (VR) systems are: 1) potential "cybersickness", and 2) maladaptive sensorimotor performance following exposure to VR systems. Interestingly, these aftereffects are often quite similar to adaptive sensorimotor responses observed in astronauts during and/or following space flight. Changes in the environmental sensory stimulus conditions and the way we interact with the new stimuli may result in motion sickness, and perceptual, spatial orientation and sensorimotor disturbances. Initial interpretation of novel sensory information may be inappropriate and result in perceptual errors. Active exploratory behavior in a new environment, with resulting feedback and the formation of new associations between sensory inputs and response outputs, promotes appropriate perception and motor control in the new environment. Thus, people adapt to consistent, sustained alterations of sensory input such as those produced by microgravity, unilateral labyrinthectomy and experimentally produced stimulus rearrangements. Adaptation is revealed by aftereffects including perceptual disturbances and sensorimotor control disturbances. The purpose of the current study was to compare disturbances in postural control produced by dome and head-mounted virtual environment displays, and to examine the effects of exposure duration, and repeated exposures to VR systems. Forty-one subjects (21 men, 20 women) participated in the study with an age range of 21-49 years old. One training session was completed in order to achieve stable performance on the posture and VR tasks before participating in the experimental sessions. Three experimental sessions were performed each separated by one day. The subjects performed a navigation and pick and place task in either a dome or head-mounted display
Malolepsza, Edyta; Kim, Jaegil; Keyes, Tom
2015-04-28
Metastable β ice holds small guest molecules in stable gas hydrates, so its solid/liquid equilibrium is of interest. However, aqueous crystal/liquid transitions are very difficult to simulate. A new MD algorithm generates trajectories in a generalized NPT ensemble and equilibrates states of coexisting phases with a selectable enthalpy. Furthermore, with replicas spanning the range between β ice and liquid water we find the statistical temperature from the enthalpy histograms and characterize the transition by the entropy, introducing a general computational procedure for first-order transitions.
Regularized model of post-touchdown configurations in electrostatic MEMS: Equilibrium analysis
NASA Astrophysics Data System (ADS)
Lindsay, A. E.; Lega, J.; Glasner, K. B.
2014-07-01
In canonical models of Micro-Electro Mechanical Systems (MEMS), an event called touchdown whereby the electrical components of the device come into contact, is characterized by a blow up in the governing equations and a non-physical divergence of the electric field. In the present work, we propose novel regularized governing equations whose solutions remain finite at touchdown and exhibit additional dynamics beyond this initial event before eventually relaxing to new stable equilibria. We employ techniques from variational calculus, dynamical systems and singular perturbation theory to obtain a detailed understanding of the properties and equilibrium solutions of the regularized family of equations.
Evaluation of the information content of sedimentation equilibrium data in self-interacting systems.
Ang, Shirley; Rowe, Arthur J
2010-07-07
Fitting r = f(c) as opposed to the usual c = f(r) to the inverted form of the sedimentation equilibrium equation for interacting solute (INVEQ algorithm), it is shown by detailed simulation and by experimentation that stable, simultaneous estimates can be retrieved for both virial (2nd BM/3rd CM) and specific interaction (K(a)) terms. In suitable systems estimates for two distinct second virial (BM) and single K(a) terms can equally be defined. Whilst cell loading level is critical, noise level in the interference fringe data is shown to have surprisingly little influence on these outcomes.
Bowler, Michael G.
2017-01-01
The humidity surrounding a sample is an important variable in scientific experiments. Biological samples in particular require not just a humid atmosphere but often a relative humidity (RH) that is in equilibrium with a stabilizing solution required to maintain the sample in the same state during measurements. The controlled dehydration of macromolecular crystals can lead to significant increases in crystal order, leading to higher diffraction quality. Devices that can accurately control the humidity surrounding crystals while monitoring diffraction have led to this technique being increasingly adopted, as the experiments become easier and more reproducible. Matching the RH to the mother liquor is the first step in allowing the stable mounting of a crystal. In previous work [Wheeler, Russi, Bowler & Bowler (2012). Acta Cryst. F68, 111–114], the equilibrium RHs were measured for a range of concentrations of the most commonly used precipitants in macromolecular crystallography and it was shown how these related to Raoult’s law for the equilibrium vapour pressure of water above a solution. However, a discrepancy between the measured values and those predicted by theory could not be explained. Here, a more precise humidity control device has been used to determine equilibrium RH points. The new results are in agreement with Raoult’s law. A simple argument in statistical mechanics is also presented, demonstrating that the equilibrium vapour pressure of a solvent is proportional to its mole fraction in an ideal solution: Raoult’s law. The same argument can be extended to the case where the solvent and solute molecules are of different sizes, as is the case with polymers. The results provide a framework for the correct maintenance of the RH surrounding a sample. PMID:28381983
Evolution of equilibrium Pickering emulsions--a matter of time scales.
Kraft, Daniela J; Luigjes, Bob; de Folter, Julius W J; Philipse, Albert P; Kegel, Willem K
2010-09-30
A new class of equilibrium solid-stabilized oil-in-water emulsions harbors a competition of two processes on disparate time scales that affect the equilibrium droplet size in opposing ways. The aim of this work is to elucidate the molecular origins of these two time scales and demonstrate their effects on the evolution of the emulsion droplet size. First, spontaneous emulsification into particle-covered droplets occurs through in situ generation of surface-active molecules by hydrolysis of molecules of the oil phase. We show that surface tensions of the oil-water interfaces in the absence of stabilizing colloidal particles are connected to the concentration of these surface-active molecules, and hence also to the equilibrium droplet size in the presence of colloids. As a consequence, the hydrolysis process sets the time scale of formation of these solid-stabilized emulsions. A second time scale is governing the ultimate fate of the solid-stabilized equilibrium emulsions: by condensation of the in situ generated amphiphilic molecules onto the colloidal particles, their wetting properties change, leading to a gradual transfer from the aqueous to the oil phase via growth of the emulsion droplets. This migration is observed macroscopically by a color change of the water and oil phases, as well as by electron microscopy after polymerization of the oil phase in a phase separated sample. Surprisingly, the relative oil volume sets the time scale of particle transfer. Phase separation into an aqueous phase and an oil phase containing colloidal particles is influenced by sedimentation of the emulsion droplets. The two processes of formation of surface-active molecules through hydrolysis and condensation thereof on the colloidal surface have an opposite influence on the droplet size. By their interplay, a dynamic equilibrium is created where the droplet size always adjusts to the thermodynamically stable state.
Bowler, Michael G; Bowler, David R; Bowler, Matthew W
2017-04-01
The humidity surrounding a sample is an important variable in scientific experiments. Biological samples in particular require not just a humid atmosphere but often a relative humidity (RH) that is in equilibrium with a stabilizing solution required to maintain the sample in the same state during measurements. The controlled dehydration of macromolecular crystals can lead to significant increases in crystal order, leading to higher diffraction quality. Devices that can accurately control the humidity surrounding crystals while monitoring diffraction have led to this technique being increasingly adopted, as the experiments become easier and more reproducible. Matching the RH to the mother liquor is the first step in allowing the stable mounting of a crystal. In previous work [Wheeler, Russi, Bowler & Bowler (2012). Acta Cryst. F68, 111-114], the equilibrium RHs were measured for a range of concentrations of the most commonly used precipitants in macromolecular crystallography and it was shown how these related to Raoult's law for the equilibrium vapour pressure of water above a solution. However, a discrepancy between the measured values and those predicted by theory could not be explained. Here, a more precise humidity control device has been used to determine equilibrium RH points. The new results are in agreement with Raoult's law. A simple argument in statistical mechanics is also presented, demonstrating that the equilibrium vapour pressure of a solvent is proportional to its mole fraction in an ideal solution: Raoult's law. The same argument can be extended to the case where the solvent and solute molecules are of different sizes, as is the case with polymers. The results provide a framework for the correct maintenance of the RH surrounding a sample.
Damos, Petros
2015-08-01
In this study, we use entropy related mixing rate modules to measure the effects of temperature on insect population stability and demographic breakdown. The uncertainty in the age of the mother of a randomly chosen newborn, and how it is moved after a finite act of time steps, is modeled using a stochastic transformation of the Leslie matrix. Age classes are represented as a cycle graph and its transitions towards the stable age distribution are brought forth as an exact Markov chain. The dynamics of divergence, from a non equilibrium state towards equilibrium, are evaluated using the Kolmogorov-Sinai entropy. Moreover, Kullback-Leibler distance is applied as information-theoretic measure to estimate exact mixing times of age transitions probabilities towards equilibrium. Using empirically data, we show that on the initial conditions and simulated projection's trough time, that population entropy can effectively be applied to detect demographic variability towards equilibrium under different temperature conditions. Changes in entropy are correlated with the fluctuations of the insect population decay rates (i.e. demographic stability towards equilibrium). Moreover, shorter mixing times are directly linked to lower entropy rates and vice versa. This may be linked to the properties of the insect model system, which in contrast to warm blooded animals has the ability to greatly change its metabolic and demographic rates. Moreover, population entropy and the related distance measures that are applied, provide a means to measure these rates. The current results and model projections provide clear biological evidence why dynamic population entropy may be useful to measure population stability.
Hirshman, S. P.; Shafer, M. W.; Seal, S. K.; Canik, J. M.
2016-03-03
The SIESTA magnetohydrodynamic (MHD) equilibrium code has been used to compute a sequence of ideally stable equilibria resulting from numerical variation of the helical resonant magnetic perturbation (RMP) applied to an axisymmetric DIII-D plasma equilibrium. Increasing the perturbation strength at the dominant m=2, n=-1 , resonant surface leads to lower MHD energies and increases in the equilibrium island widths at the m=2 (and sidebands) surfaces, in agreement with theoretical expectations. Island overlap at large perturbation strengths leads to stochastic magnetic fields which correlate well with the experimentally inferred field structure. The magnitude and spatial phase (around the dominant rational surfaces) of the resonant (shielding) component of the parallel current are shown to change qualitatively with the magnetic island topology.
Hirshman, S. P.; Shafer, M. W.; Seal, S. K.; ...
2016-03-03
The SIESTA magnetohydrodynamic (MHD) equilibrium code has been used to compute a sequence of ideally stable equilibria resulting from numerical variation of the helical resonant magnetic perturbation (RMP) applied to an axisymmetric DIII-D plasma equilibrium. Increasing the perturbation strength at the dominant m=2, n=-1 , resonant surface leads to lower MHD energies and increases in the equilibrium island widths at the m=2 (and sidebands) surfaces, in agreement with theoretical expectations. Island overlap at large perturbation strengths leads to stochastic magnetic fields which correlate well with the experimentally inferred field structure. The magnitude and spatial phase (around the dominant rational surfaces)more » of the resonant (shielding) component of the parallel current are shown to change qualitatively with the magnetic island topology.« less
Evolution of light hydrocarbon gases in subsurface processes: Constraints from chemical equilibrium
NASA Astrophysics Data System (ADS)
Sugisaki, Ryuichi; Nagamine, Koichiro
1995-06-01
The behaviour of CH 4, C 2H 6 and C 3H 8 in subsurface processes such as magma intrusion, volcanic gas discharge and natural gas generation have been examined from the viewpoint of chemical equilibrium. It seems that equilibrium among these three hydrocarbons is attainable at about 200°C. When a system at high temperatures is cooled, re-equilibration is continued until a low temperature is reached. The rate at which re-equilibration is achieved, however, steadily diminishes and, below 200°C, the reaction between the hydrocarbons stops and the gas composition at this time is frozen in, and it remains unchanged in a metastable state for a long period of geological time. Natural gas compositions from various fields have shown that, when a hydrocarbon system out of chemical equilibrium is heated, it gradually approaches equilibrium above 150°C. On the way towards equilibration, compositions of thermogenic gases apparently temporarily show a thermodynamic equilibrium constant at a temperature that is higher than the real equilibrium temperature expected from the ambient temperature of the samples; in contrast, biogenic gases indicate a lower temperature. In lower temperature regions, kinetic effects probably control the gas composition; the compositions are essentially subjected to genetic processes operating on the gases (such as pyrolysis of organic material and bacterial activity) and they fluctuate substantially. Examination of volcanic gases and pyrolysis experimental data, however, have suggested that the equilibration rate of these hydrocarbons is sluggish in comparison with that of reactive inorganic species such as H 2S and SO 2. The view presented in this study will be helpful in understanding the genetic processes that create oil and gas and the migration of these hydrocarbons and in interpreting the origins of magmatic gases.
Theoretical prediction for several important equilibrium Ge isotope fractionation factors
NASA Astrophysics Data System (ADS)
Tang, M.; Li, X.; Liu, Y.
2008-12-01
As a newly emerging field, the stable isotope geochemistry of germanium (Ge) needs basic equilibrium fractionation factors to explore its unknown world. In this study, the Ge isotope fractionations between systems including the aqueous Ge(OH)4 and GeO(OH)3- which are the dominant Ge species in seawater, the Ge-bearing organic complexes (e.g. Ge-catechol, Ge-oxalic acid and Ge-citric acid), the quartz- (or opal- ), albite-, K-feldspar- and olivine- like mineral structures are studied. It is the first time that some geologically important equilibrium Ge isotope fractionation factors are reported. Surprisingly, up to 5 per mil large isotopic fractionations between these Ge isotope systems are found at 25 degree. These results suggest a potentially broad application for the Ge isotope geochemistry. Our theoretical calculations are based on the Urey model (or Bigeleisen-Mayer equation) and high level quantum chemistry calculations. The B3LYP/6-311+G(d,p) level quantum chemistry method and the explicit solvent model ("water droplet" method) are used. Many different conformers are also used for the aqueous complexes in order to reduce the possible errors coming from the differences of configurations in solution. The accuracy of our calculation of the Ge isotopic fractionations is estimated about 0.2 per mil. Our results show quartz-like or opal-like structure can enrich most heavy Ge isotopes. Relative to quartz (or opal), some Ge isotopic fractionations are (at 25 C): quartz-organic Ge = 4-5,quartz-Ge(OH)4 =0.9,quartz-GeO(OH)3- =1.5,quartz-albite=0.6,quartz-K-feldspar=0.4 and quartz-olivine=3.9 per mil. The large fractionations between inorganic Ge complexes and organic Ge ones could be used to distinguish the possible bio-involving processes. Our results suggest a good explanation to the experimental observations of Siebert et al. (2006) and Rouxel et al. (2006) and provide important constraints to the study of Ge cycle in ocean.
Phase stable RF transport system
Curtin, Michael T.; Natter, Eckard F.; Denney, Peter M.
1992-01-01
An RF transport system delivers a phase-stable RF signal to a load, such as an RF cavity of a charged particle accelerator. A circuit generates a calibration signal at an odd multiple frequency of the RF signal where the calibration signal is superimposed with the RF signal on a common cable that connects the RF signal with the load. Signal isolating diplexers are located at both the RF signal source end and load end of the common cable to enable the calibration to be inserted and extracted from the cable signals without any affect on the RF signal. Any phase shift in the calibration signal during traverse of the common cable is then functionally related to the phase shift in the RF signal. The calibration phase shift is used to control a phase shifter for the RF signal to maintain a stable RF signal at the load.
Advanced Thermally Stable Jet Fuels
A. Boehman; C. Song; H. H. Schobert; M. M. Coleman; P. G. Hatcher; S. Eser
1998-01-01
The Penn State program in advanced thermally stable jet fuels has five components: 1) development of mechanisms of degradation and solids formation; 2) quantitative measurement of growth of sub-micrometer and micrometer-sized particles during thermal stressing; 3) characterization of carbonaceous deposits by various instrumental and microscopic methods; 4) elucidation of the role of additives in retarding the formation of carbonaceous solids; and 5) assessment of the potential of producing high yields of cycloalkanes and hydroaromatics from coal.
Fluctuations in Hertz chains at equilibrium
NASA Astrophysics Data System (ADS)
Przedborski, Michelle; Sen, Surajit; Harroun, Thad A.
2017-03-01
We examine the long-term behavior of nonintegrable, energy-conserved, one-dimensional systems of macroscopic grains interacting via a contact-only generalized Hertz potential and held between stationary walls. Such systems can be set up to have no phononic background excitation and represent examples of a sonic vacuum. Existing dynamical studies showed the absence of energy equipartitioning in such systems, hence their long-term dynamics was described as quasiequilibrium. Here we show that these systems do in fact reach thermal equilibrium at sufficiently long times, as indicated by the calculated heat capacity. As a by-product, we show how fluctuations of system quantities, and thus the distribution functions, are influenced by the Hertz potential. In particular, the variance of the system's kinetic energy probability density function is reduced by a factor related to the contact potential.
LAPS discretization and solution of plasma equilibrium
NASA Astrophysics Data System (ADS)
Missanelli, Maria; Delzanno, Gian Luca; Guo, Zehua; Srinivasan, Bhuvana; Tang, Xianzhu
2011-10-01
LAPS provides spectral element discretization for solving steady state plasma profiles. Our initial focus is on its implementation for two dimensional open magnetic field equilibria in linear and toroidal geometries. The linear geometry is an axisymmetric magnetic mirror with anisotropic pressure. The toroidal case is a tokamak scrape-off layer plasma. Structured grids are produced by the grid generation package in LAPS. The spectral element discretization uses modal bases over quadrilateral elements. A Newton-Krylov solver implemented with the Portable, Extensible Toolkits for Scientific Computing PETSc is applied to iteratively converge the solution. Care has been taken in the code design to separate the grid generation, spectral element discretization, and (non)linear solver from the user-specified equilibrium equations, so the LAPS infrastructure can be easily used for different applications. Work supported by DOE OFES.
Anisotropic pressure tokamak equilibrium and stability considerations
Salberta, E.R.; Grimm, R.C.; Johnson, J.L.; Manickam, J.; Tang, W.M.
1987-02-01
Investigation of the effect of pressure anisotropy on tokamak equilibrium and stability is made with an MHD model. Realistic perpendicular and parallel pressure distributions, P/sub perpendicular/(psi,B) and P/sub parallel/(psi,B), are obtained by solving a one-dimensional Fokker-Planck equation for neutral beam injection to find a distribution function f(E, v/sub parallel//v) at the position of minimum field on each magnetic surface and then using invariance of the magnetic moment to determine its value at each point on the surface. The shift of the surfaces of constant perpendicular and parallel pressure from the flux surfaces depends strongly on the angle of injection. This shift explains the observed increase or decrease in the stability conditions. Estimates of the stabilizing effect of hot trapped ions indicates that a large fraction must be nonresonant and thus decoupled from the bad curvature before it becomes important.
Equilibrium properties of chemically reacting gases
NASA Technical Reports Server (NTRS)
1976-01-01
The equilibrium energy, enthalpy, entropy, specific heat at constant volume and constant pressure, and the equation of state of the gas are all derived for chemically reacting gas mixtures in terms of the compressibility, the mol fractions, the thermodynamic properties of the pure gas components, and the change in zero point energy due to reaction. Results are illustrated for a simple diatomic dissociation reaction and nitrogen is used as an example. Next, a gas mixture resulting from combined diatomic dissociation and atomic ionization reactions is treated and, again, nitrogen is used as an example. A short discussion is given of the additional complexities involved when precise solutions for high-temperature air are desired, including effects caused by NO produced in shuffle reactions and by other trace species formed from CO2, H2O and Ar found in normal air.
Radiative equilibrium model of Titan's atmosphere
NASA Technical Reports Server (NTRS)
Samuelson, R. E.
1983-01-01
The present global radiative equilibrium model for the Saturn satellite Titan is restricted to the two-stream approximation, is vertically homogeneous in its scattering properties, and is spectrally divided into one thermal and two solar channels. Between 13 and 33% of the total incident solar radiation is absorbed at the planetary surface, and the 30-60 ratio of violet to thermal IR absorption cross sections in the stratosphere leads to the large temperature inversion observed there. The spectrally integrated mass absorption coefficient at thermal wavelengths is approximately constant throughout the stratosphere, and approximately linear with pressure in the troposphere, implying the presence of a uniformly mixed aerosol in the stratosphere. There also appear to be two regions of enhanced opacity near 30 and 500 mbar.
Kinetics of allophycocyanin's trimer-monomer equilibrium.
Huang, C; Berns, D S; MacColl, R
1987-01-13
Kinetic studies of the dissociation of allophycocyanin trimers to monomers have been performed by using stopped-flow techniques. The dissociation was monitored by two techniques: by light scattering to observe the molecular weight changes directly and by 650-nm absorbance to observe the linkage of quaternary structure to spectra. The light-scattering experiments showed a simple exponential decay of trimers to monomers with a dissociation constant of 0.23 s-1. The absorption changes were complex, with two processes occurring. The faster absorption change appeared to be almost simultaneous with the molecular weight change (about 0.27 s-1) and was perhaps totally coordinated with it. The slower absorption change (0.071 s-1) was possibly a result of a conformational change in the chromophore arising during the conversion from newly dissociated monomers to equilibrium monomers.
Radiative equilibrium model of Titan's atmosphere
NASA Astrophysics Data System (ADS)
Samuelson, R. E.
1983-02-01
The present global radiative equilibrium model for the Saturn satellite Titan is restricted to the two-stream approximation, is vertically homogeneous in its scattering properties, and is spectrally divided into one thermal and two solar channels. Between 13 and 33% of the total incident solar radiation is absorbed at the planetary surface, and the 30-60 ratio of violet to thermal IR absorption cross sections in the stratosphere leads to the large temperature inversion observed there. The spectrally integrated mass absorption coefficient at thermal wavelengths is approximately constant throughout the stratosphere, and approximately linear with pressure in the troposphere, implying the presence of a uniformly mixed aerosol in the stratosphere. There also appear to be two regions of enhanced opacity near 30 and 500 mbar.
Dynamic Protonation Equilibrium of Solvated Acetic Acid
Gu, Wei; Frigato, Tomaso; Straatsma, TP; Helms, Volkhard H.
2007-04-13
For the first time, the dynamic protonation equilibrium between an amino acid side chain analogue and bulk water as well as the diffusion properties of the excess proton were successfully reproduced through unbiased computer simulations. During a 50 ns Q-HOP MD simulation, two different regimes of proton transfer were observed. Extended phases of frequent proton swapping between acetic acid and nearby water were separated by phases where the proton freely diffuses in the simulation box until it is captured again by acetic acid. The pKa of acetic acid was calculated around 3.0 based on the relative population of protonated and deprotonated states and the diffusion coefficient of excess proton was computed from the average mean squared displacement in the simulation. Both calculated values agree well with the experimental measurements.
Equilibrium Phase Behavior of Polydisperse Hard Spheres
NASA Astrophysics Data System (ADS)
Fasolo, Moreno; Sollich, Peter
2003-08-01
We calculate the phase behavior of hard spheres with size polydispersity, using accurate free energies for the fluid and solid phases. Cloud and shadow curves are found exactly by the moment free energy method, but we also compute the complete phase diagram, taking full account of fractionation. In contrast to earlier, simplified treatments we find no point of equal concentration between fluid and solid or reentrant melting at higher densities. Rather, the fluid cloud curve continues to the largest polydispersity that we study (14%); from the equilibrium phase behavior a terminal polydispersity can thus be defined only for the solid, where we find it to be around 7%. At sufficiently large polydispersity, fractionation into several solid phases can occur, consistent with previous approximate calculations; we find, in addition, that coexistence of several solids with a fluid phase is also possible.
The equilibrium size distribution of rouleaux.
Perelson, A S; Wiegel, F W
1982-01-01
Rouleaux are formed by the aggregation of red blood cells in the presence of macromolecules that bridge the membranes of adherent erythrocytes. We compute the size and degree of branching of rouleaux for macroscopic systems in thermal equilibrium in the absence of fluid flow. Using techniques from statistical mechanics, analytical expressions are derived for (a) the average number of rouleaux consisting of n cells and having m branch points; (b) the average number of cells per rouleau; (c) the average number of branch points per rouleau; and (d) the number of rouleaux with n cells, n = 1, 2, ..., in a system containing a total of N cells. We also present the results of numerical evaluations to establish the validity of asymptotic expressions that simplify our formal analytic results. Images FIGURE 1 PMID:7059653
Phase-field model of oxidation: Equilibrium
NASA Astrophysics Data System (ADS)
Sherman, Q. C.; Voorhees, P. W.
2017-03-01
A phase-field model of an oxide relevant to corrosion resistant alloys for film thicknesses below the Debye length LD, where charge neutrality in the oxide does not occur, is formulated. The phase-field model is validated in the Wagner limit using a sharp interface Gouy-Chapman model for the electrostatic double layer. The phase-field simulations show that equilibrium oxide films below the Wagner limit are charged throughout due to their inability to electrostatically screen charge over the length of the film, L . The character of the defect and charge distribution profiles in the oxide vary depending on whether reduced oxygen adatoms are present on the gas-oxide interface. The Fermi level in the oxide increases for thinner films, approaching the Fermi level of the metal in the limit L /LD→0 , which increases the driving force for adsorbed oxygen reduction at the gas-oxide interface.
Hall MHD Equilibrium of Accelerated Compact Toroids
NASA Astrophysics Data System (ADS)
Howard, S. J.; Hwang, D. Q.; Horton, R. D.; Evans, R. W.; Brockington, S. J.
2007-11-01
We examine the structure and dynamics of the compact toroid's magnetic field. The compact toroid is dramatically accelerated by a large rail-gun Lorentz force density equal to j xB. We use magnetic data from the Compact Toroid Injection Experiment to answer the question of exactly where in the system j xB has nonzero values, and to what extent we can apply the standard model of force-free equilibrium. In particular we present a method of analysis of the magnetic field probe signals that allows direct comparison to the predictions of the Woltjer-Taylor force-free model and Turner's generalization of magnetic relaxation in the presence of a non-zero Hall term and fluid vorticity.
Approach to Equilibrium for the Stochastic NLS
NASA Astrophysics Data System (ADS)
Lebowitz, J. L.; Mounaix, Ph.; Wang, W.-M.
2013-07-01
We study the approach to equilibrium, described by a Gibbs measure, for a system on a d-dimensional torus evolving according to a stochastic nonlinear Schrödinger equation (SNLS) with a high frequency truncation. We prove exponential approach to the truncated Gibbs measure both for the focusing and defocusing cases when the dynamics is constrained via suitable boundary conditions to regions of the Fourier space where the Hamiltonian is convex. Our method is based on establishing a spectral gap for the non self-adjoint Fokker-Planck operator governing the time evolution of the measure, which is uniform in the frequency truncation N. The limit N →∞ is discussed.
Information thermodynamics of near-equilibrium computation
NASA Astrophysics Data System (ADS)
Prokopenko, Mikhail; Einav, Itai
2015-06-01
In studying fundamental physical limits and properties of computational processes, one is faced with the challenges of interpreting primitive information-processing functions through well-defined information-theoretic as well as thermodynamic quantities. In particular, transfer entropy, characterizing the function of computational transmission and its predictability, is known to peak near critical regimes. We focus on a thermodynamic interpretation of transfer entropy aiming to explain the underlying critical behavior by associating information flows intrinsic to computational transmission with particular physical fluxes. Specifically, in isothermal systems near thermodynamic equilibrium, the gradient of the average transfer entropy is shown to be dynamically related to Fisher information and the curvature of system's entropy. This relationship explicitly connects the predictability, sensitivity, and uncertainty of computational processes intrinsic to complex systems and allows us to consider thermodynamic interpretations of several important extreme cases and trade-offs.
Dissipation in non-equilibrium turbulence
NASA Astrophysics Data System (ADS)
Bos, Wouter; Rubinstein, Robert
2016-11-01
For about a decade, experimental and numerical studies have reported on the existence of an anomalous behaviour of the viscous dissipation rate in unsteady turbulence (see for instance Vassilicos, Annu. Rev. Fluid Mech. 2015). It appears that the short-time transient dynamics can be described by a universal power law, incompatible with Taylor's 1935 dissipation rate estimate. We show that these results can be explained using a non-equilibrium energy distribution, obtained from a low-frequency perturbative expansion of simple spectral closure. The resulting description is fairly simple. In particular, during the transient, according to the predictions, the normalized dissipation rate Cɛ evolves as a function of the Taylor-scale Reynolds number Rλ following the relation Cɛ Rλ- 15 / 14 , in close agreement with experimental and numerical observations.
Information thermodynamics of near-equilibrium computation.
Prokopenko, Mikhail; Einav, Itai
2015-06-01
In studying fundamental physical limits and properties of computational processes, one is faced with the challenges of interpreting primitive information-processing functions through well-defined information-theoretic as well as thermodynamic quantities. In particular, transfer entropy, characterizing the function of computational transmission and its predictability, is known to peak near critical regimes. We focus on a thermodynamic interpretation of transfer entropy aiming to explain the underlying critical behavior by associating information flows intrinsic to computational transmission with particular physical fluxes. Specifically, in isothermal systems near thermodynamic equilibrium, the gradient of the average transfer entropy is shown to be dynamically related to Fisher information and the curvature of system's entropy. This relationship explicitly connects the predictability, sensitivity, and uncertainty of computational processes intrinsic to complex systems and allows us to consider thermodynamic interpretations of several important extreme cases and trade-offs.
Equilibrium Structure of Tantalum Oxygen Clusters
NASA Astrophysics Data System (ADS)
Dalgic, S. Sentürk; Caliskan, M.
2007-04-01
We determine a refined model for the interionic interactions in TaOn clusters by an analysis of data on their molecular structures. The potential energy function of an ionic cluster we adopt is based on the interionic force model proposed by Akdeniz and Tosi. The microscopic model used for Tantalum oxygen clusters incorporates the Born Model of cohesion and shell model for vibrational motions and crystal defects. Electron shell deformability is described through the effective valences, the electric and overlap polarizabilities of the oxygens, the electric polarizability of the tantalum ions. The two different overlap repulsive energy form have been tested. The molecular structure of clusters in equilibrium have been shown. It has been found in a good agreement for the bond lengths and bond angles by comparing with those obtained by chemical structure calculations and experimental data Thus the applicability of interionic model is tested for transition metal oxide clusters.
Plasmon damping in graphene out of equilibrium
NASA Astrophysics Data System (ADS)
Sun, Zhiyuan; Basov, Dimitri; Fogler, Michael
Motivated by recent experiments with graphene under high photoexcitation, we study theoretically plasmons of graphene in the two-temperature regime, i.e., the regime where electrons are much hotter than the lattice. We calculate the plasmon damping due to scattering of electrons by acoustic phonons, which is the dominant intrinsic contribution in clean graphene. As the system relaxes to equilibrium, the plasmon frequency adiabatically changes with time. We show that this causes a partial compensation of the plasmon damping. A similar mechanism may apply to another collective mode (the energy wave) predicted to exist in graphene in the low-frequency hydrodynamic regime. Implications for infrared and THz pump-probe experiments are discussed.
Dynamic Stability of Equilibrium Capillary Drops
NASA Astrophysics Data System (ADS)
Feldman, William M.; Kim, Inwon C.
2014-03-01
We investigate a model for contact angle motion of quasi-static capillary drops resting on a horizontal plane. We prove global in time existence and long time behavior (convergence to equilibrium) in a class of star-shaped initial data for which we show that topological changes of drops can be ruled out for all times. Our result applies to any drop which is initially star-shaped with respect to a small ball inside the drop, given that the volume of the drop is sufficiently large. For the analysis, we combine geometric arguments based on the moving-plane type method with energy dissipation methods based on the formal gradient flow structure of the problem.
Punctuated equilibrium dynamics in human communications
NASA Astrophysics Data System (ADS)
Peng, Dan; Han, Xiao-Pu; Wei, Zong-Wen; Wang, Bing-Hong
2015-10-01
A minimal model based on network incorporating individual interactions is proposed to study the non-Poisson statistical properties of human behavior: individuals in system interact with their neighbors, the probability of an individual acting correlates to its activity, and all the individuals involved in action will change their activities randomly. The model reproduces varieties of spatial-temporal patterns observed in empirical studies of human daily communications, providing insight into various human activities and embracing a range of realistic social interacting systems, particularly, intriguing bimodal phenomenon. This model bridges priority queueing theory and punctuated equilibrium dynamics, and our modeling and analysis is likely to shed light on non-Poisson phenomena in many complex systems.
Nash equilibrium and multi criterion aerodynamic optimization
NASA Astrophysics Data System (ADS)
Tang, Zhili; Zhang, Lianhe
2016-06-01
Game theory and its particular Nash Equilibrium (NE) are gaining importance in solving Multi Criterion Optimization (MCO) in engineering problems over the past decade. The solution of a MCO problem can be viewed as a NE under the concept of competitive games. This paper surveyed/proposed four efficient algorithms for calculating a NE of a MCO problem. Existence and equivalence of the solution are analyzed and proved in the paper based on fixed point theorem. Specific virtual symmetric Nash game is also presented to set up an optimization strategy for single objective optimization problems. Two numerical examples are presented to verify proposed algorithms. One is mathematical functions' optimization to illustrate detailed numerical procedures of algorithms, the other is aerodynamic drag reduction of civil transport wing fuselage configuration by using virtual game. The successful application validates efficiency of algorithms in solving complex aerodynamic optimization problem.
NASA Astrophysics Data System (ADS)
McCarroll, Danny; Loader, Neil J.
2004-04-01
Stable isotopes in tree rings could provide palaeoclimate reconstructions with perfect annual resolution and statistically defined confidence limits. Recent advances make the approach viable for non-specialist laboratories. The relevant literature is, however, spread across several disciplines, with common problems approached in different ways. Here we provide the first overview of isotope dendroclimatology, explaining the underlying theory and describing the steps taken in building and interpreting isotope chronologies. Stable carbon isotopes record the balance between stomatal conductance and photosynthetic rate, dominated at dry sites by relative humidity and soil water status and at moist sites by summer irradiance and temperature. Stable oxygen and hydrogen isotopic ratios record source water, which contains a temperature signal, and leaf transpiration, controlled dominantly by vapour pressure deficit. Variable exchange with xylem (source) water during wood synthesis determines the relative strength of the source water and leaf enrichment signals. Producing long Holocene chronologies will require a change in emphasis towards processing very large numbers of samples efficiently, whilst retaining analytical precision. A variety of sample preparation and data treatment protocols have been used, some of which have a deleterious effect on the palaeoclimate signal. These are reviewed and suggestions made for a more standardised approach.
A Progression of Static Equilibrium Laboratory Exercises
NASA Astrophysics Data System (ADS)
Kutzner, Mickey; Kutzner, Andrew
2013-10-01
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 textbooks, these two conditions appear as ΣF=0(1) and Στ=0,(2) where each torque τ is defined as the cross product between the lever arm vector r and the corresponding applied force F, τ =r×F,(3) having magnitude, τ =Frsinθ.(4) The angle θ here is between the two vectors F and r. In Eq. (1), upward (downward) forces are considered positive (negative). In Eq. (2), counterclockwise (clockwise) torques are considered positive (negative). Equation (1) holds that the vector sum of the external forces acting on an object must be zero to prevent linear accelerations; Eq. (2) states that the vector sum of torques due to external forces about any axis must be zero to prevent angular accelerations. In our view these conditions can be problematic for students because a) the equations contain the unfamiliar summation notation Σ, b) students are uncertain of the role of torques in causing rotations, and c) it is not clear why the sum of torques is zero regardless of the choice of axis. Gianino5 describes an experiment using MBL and a force sensor to convey the meaning of torque as applied to a rigid-body lever system without exploring quantitative aspects of the conditions for static equilibrium.
Uncertainty Quantification of Equilibrium Climate Sensitivity
NASA Astrophysics Data System (ADS)
Lucas, D. D.; Brandon, S. T.; Covey, C. C.; Domyancic, D. M.; Johannesson, G.; Klein, R.; Tannahill, J.; Zhang, Y.
2011-12-01
Significant uncertainties exist in the temperature response of the climate system to changes in the levels of atmospheric carbon dioxide. We report progress to quantify the uncertainties of equilibrium climate sensitivity using perturbed parameter ensembles of the Community Earth System Model (CESM). Through a strategic initiative at the Lawrence Livermore National Laboratory, we have been developing uncertainty quantification (UQ) methods and incorporating them into a software framework called the UQ Pipeline. We have applied this framework to generate a large number of ensemble simulations using Latin Hypercube and other schemes to sample up to three dozen uncertain parameters in the atmospheric (CAM) and sea ice (CICE) model components of CESM. The parameters sampled are related to many highly uncertain processes, including deep and shallow convection, boundary layer turbulence, cloud optical and microphysical properties, and sea ice albedo. An extensive ensemble database comprised of more than 46,000 simulated climate-model-years of recent climate conditions has been assembled. This database is being used to train surrogate models of CESM responses and to perform statistical calibrations of the CAM and CICE models given observational data constraints. The calibrated models serve as a basis for propagating uncertainties forward through climate change simulations using a slab ocean model configuration of CESM. This procedure is being used to quantify the probability density function of equilibrium climate sensitivity accounting for uncertainties in climate model processes. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and was funded by the Uncertainty Quantification Strategic Initiative Laboratory Directed Research and Development Project at LLNL under project tracking code 10-SI-013. (LLNL-ABS-491765)
Iudicello, Jennifer E; Woods, Steven P; Vigil, Ofilio; Scott, J Cobb; Cherner, Mariana; Heaton, Robert K; Atkinson, J Hampton; Grant, Igor
2010-08-01
Chronic use of methamphetamine (MA) is associated with neuropsychological dysfunction and affective distress. Some normalization of function has been reported after abstinence, but little in the way of data is available on the possible added benefits of long-term sobriety. To address this, we performed detailed neuropsychological and affective evaluations in 83 MA-dependent individuals at a baseline visit and following an average one-year interval period. Among the 83 MA-dependent participants, 25 remained abstinent, and 58 used MA at least once during the interval period. A total of 38 non-MA-addicted, demographically matched healthy comparison (i.e., HC) participants were also examined. At baseline, both MA-dependent participants who were able to maintain abstinence and those who were not performed significantly worse than the healthy comparison subjects on global neuropsychological functioning and were significantly more distressed. At the one-year follow-up, both the long-term abstainers and healthy comparison groups showed comparable global neuropsychological performance and affective distress levels, whereas the MA-dependent group who continued to use MA were worse than the comparison participants in terms of global neuropsychological functioning and affective distress. An interaction was observed between neuropsychological impairment at baseline, MA abstinence, and cognitive improvement, with abstinent MA-dependent participants who were neuropsychologically impaired at baseline demonstrating significantly and disproportionately greater improvement in processing speed and slightly greater improvement in motor abilities than the other participants. These results suggest partial recovery of neuropsychological functioning and improvement in affective distress upon sustained abstinence from MA that may extend beyond a year or more.
Superior Stable and Long Life Sodium Metal Anodes Achieved by Atomic Layer Deposition.
Zhao, Yang; Goncharova, Lyudmila V; Lushington, Andrew; Sun, Qian; Yadegari, Hossein; Wang, Biqiong; Xiao, Wei; Li, Ruying; Sun, Xueliang
2017-03-03
Na-metal batteries are considered as the promising alternative candidate for Li-ion battery beneficial from the wide availability and low cost of sodium, high theoretical specific capacity, and high energy density based on the plating/stripping processes and lowest electrochemical potential. For Na-metal batteries, the crucial problem on metallic Na is one of the biggest challenges. Mossy or dendritic growth of Na occurs in the repetitive Na stripping/plating process with an unstable solid electrolyte interphase layer of nonuniform ionic flux, which can not only lead to the low Coulombic efficiency, but also can create short circuit risks, resulting in possible burning or explosion. In this communication, the atomic layer deposition of Al2 O3 coating is first demonstrated for the protection of metallic Na anode for Na-metal batteries. By protecting Na foil with ultrathin Al2 O3 layer, the dendrites and mossy Na formation have been effectively suppressed and lifetime has been significantly improved. Furthermore, the thickness of protective layer has been further optimized with 25 cycles of Al2 O3 layer presenting the best performance over 500 cycles. The novel design of atomic layer deposition protected metal Na anode may bring in new opportunities to the realization of the next-generation high energy-density Na metal batteries.
Conformation equilibrium of 3-(hydroxymethyl)piperidine in solvents with different polarity
NASA Astrophysics Data System (ADS)
Korneichuk, A. Ya.; Senyavin, V. M.; Kuramshina, G. M.
2017-02-01
Quantum-chemical calculations of the 3-(hydroxymethyl)piperidine molecule conformers were performed at the B3LYP/6-31+G** level of theory, and four most stable conformations with different relative orientation of CH2OH and N-H groups were determined. The optimized structures, vibration frequencies, and band intensities in the spectra of the conformers were obtained. The conformational equilibria of the most stable rotational isomers in solvents of different polarity was studied within the polarizable continuum model. According to the results of calculations, the conformational equilibrium in solution is substantially changed on varying the solvent polarity. This conclusion was confirmed by comparison with IR absorption spectra of 3-(hydroxymethyl)piperidine solutions in carbon tetrachloride in the region of OH-stretchings.
LP based approach to optimal stable matchings
Teo, Chung-Piaw; Sethuraman, J.
1997-06-01
We study the classical stable marriage and stable roommates problems using a polyhedral approach. We propose a new LP formulation for the stable roommates problem. This formulation is non-empty if and only if the underlying roommates problem has a stable matching. Furthermore, for certain special weight functions on the edges, we construct a 2-approximation algorithm for the optimal stable roommates problem. Our technique uses a crucial geometry of the fractional solutions in this formulation. For the stable marriage problem, we show that a related geometry allows us to express any fractional solution in the stable marriage polytope as convex combination of stable marriage solutions. This leads to a genuinely simple proof of the integrality of the stable marriage polytope. Based on these ideas, we devise a heuristic to solve the optimal stable roommates problem. The heuristic combines the power of rounding and cutting-plane methods. We present some computational results based on preliminary implementations of this heuristic.
Space Stable Thermal Control Coatings.
1987-05-01
recommended procedure of adding additional crosslinker ,4 was followed for achieving a polymerized coating. All formulations were ball milled using half...results with R2602 were achieved by using large amounts of crosslinker and catalyst as recommended by the manufacturer. Experiments were also conducted...formulated using a one-part resin system incor- porating the resin, catalyst ( crosslinker ), and some solvents into a single package. The one-part
ERIC Educational Resources Information Center
Bilgin, Ibrahim; Geban, Omer
2006-01-01
The purpose of this study is to investigate the effects of the cooperative learning approach based on conceptual change conditions over traditional instruction on 10th grade students' conceptual understanding and achievement of computational problems related to chemical equilibrium concepts. The subjects of this study consisted of 87 tenth grade…
NASA Astrophysics Data System (ADS)
Walters, Wendell W.; Michalski, Greg
2016-10-01
The oxygen stable isotope composition (δ18O) of nitrogen oxides [NOx = nitric oxide (NO) + nitrogen dioxide (NO2)] and their oxidation products (NOy = NOx + nitric acid (HNO3) + particulate nitrate (p-NO3-) + nitrate radical (NO3) + dinitrogen pentoxide (N2O5) + nitrous acid (HONO) + …) have been shown to be a useful tool for inferring the proportion of NOx that is oxidized by ozone (O3). However, isotopic fractionation processes may have an influence on δ18O of various NOy molecules and other atmospheric O-bearing molecules pertinent to NOx oxidation chemistry. Here we have evaluated the impacts of O isotopic exchange involving NOy molecules, the hydroxyl radical (radOH), and water (H2O) using reduced partition function ratios (xβ) calculated by hybrid density functional theory. Assuming atmospheric isotopic equilibrium is achieved between NO and NO2 during the daytime, and NO2, NO3, and N2O5 during the nighttime, δ18O-δ15N compositions were predicted for the major atmospheric nitrate formation pathways using our calculated exchange fractionation factors and isotopic mass-balance. Our equilibrium model predicts that various atmospheric nitrate formation pathways, including NO2 + radOH → HNO3, N2O5 + H2O + surface → 2HNO3, and NO3 + R → HNO3 + Rrad will yield distinctive δ18O-δ15N compositions. Our calculated δ18O-δ15N compositions match well with previous atmospheric nitrate measurements, and will potentially help better understand the role oxidation chemistry plays on the N and O isotopic composition of atmospheric nitrate.
Equilibrium chemical vapor deposition growth of Bernal-stacked bilayer graphene.
Zhao, Pei; Kim, Sungjin; Chen, Xiao; Einarsson, Erik; Wang, Miao; Song, Yenan; Wang, Hongtao; Chiashi, Shohei; Xiang, Rong; Maruyama, Shigeo
2014-11-25
Using ethanol as the carbon source, self-limiting growth of AB-stacked bilayer graphene (BLG) has been achieved on Cu via an equilibrium chemical vapor deposition (CVD) process. We found that during this alcohol catalytic CVD (ACCVD) a source-gas pressure range exists to break the self-limitation of monolayer graphene on Cu, and at a certain equilibrium state it prefers to form uniform BLG with a high surface coverage of ∼94% and AB-stacking ratio of nearly 100%. More importantly, once the BLG is completed, this growth shows a self-limiting manner, and an extended ethanol flow time does not result in additional layers. We investigate the mechanism of this equilibrium BLG growth using isotopically labeled (13)C-ethanol and selective surface aryl functionalization, and results reveal that during the equilibrium ACCVD process a continuous substitution of graphene flakes occurs to the as-formed graphene and the BLG growth follows a layer-by-layer epitaxy mechanism. These phenomena are significantly in contrast to those observed for previously reported BLG growth using methane as precursor.
Good-enough linguistic representations and online cognitive equilibrium in language processing.
Karimi, Hossein; Ferreira, Fernanda
2016-01-01
We review previous research showing that representations formed during language processing are sometimes just "good enough" for the task at hand and propose the "online cognitive equilibrium" hypothesis as the driving force behind the formation of good-enough representations in language processing. Based on this view, we assume that the language comprehension system by default prefers to achieve as early as possible and remain as long as possible in a state of cognitive equilibrium where linguistic representations are successfully incorporated with existing knowledge structures (i.e., schemata) so that a meaningful and coherent overall representation is formed, and uncertainty is resolved or at least minimized. We also argue that the online equilibrium hypothesis is consistent with current theories of language processing, which maintain that linguistic representations are formed through a complex interplay between simple heuristics and deep syntactic algorithms and also theories that hold that linguistic representations are often incomplete and lacking in detail. We also propose a model of language processing that makes use of both heuristic and algorithmic processing, is sensitive to online cognitive equilibrium, and, we argue, is capable of explaining the formation of underspecified representations. We review previous findings providing evidence for underspecification in relation to this hypothesis and the associated language processing model and argue that most of these findings are compatible with them.
GA-based stable control for a class of underactuated mechanical systems
NASA Astrophysics Data System (ADS)
Liu, Diantong; Guo, Weiping; Yi, Jianqiang
2005-12-01
A nonlinear dynamic model of a class of underactuated mechanical systems was built using the Lagrangian method. Some system properties such as the system passivity were analyzed. A GA(Genetic Algorithms)-based stable control algorithm was proposed for the class of underactuated mechanical systems. The Lyapunov stability theory and system properties were utilized to guarantee the system's asymptotic stability to its equilibrium. A real-valued GA was used to adjust the parameters of a stable controller to improve the system performance. An underactuated double-pendulum-type overhead crane system is used to validate the proposed control algorithm. Simulation results illustrate the validity of proposed control algorithm under different conditions.
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
Lifting Minority Achievement: Complex Answers. The Achievement Gap.
ERIC Educational Resources Information Center
Viadero, Debra; Johnston, Robert C.
2000-01-01
This fourth in a four-part series on why academic achievement gaps exist describes the Minority Achievement Committee scholars program at Shaker Heights High School in Cleveland, Ohio, a powerful antidote to the achievement gap between minority and white and Asian American students. It explains the need to break down stereotypes about academic…
Achievement Motivation of Women: Effects of Achievement and Affiliation Arousal.
ERIC Educational Resources Information Center
Gama, Elizabeth Maria Pinheiro
1985-01-01
Assigned 139 Brazilian women to neutral, affiliation arousal, and achievement arousal conditions based on their levels of achievement (Ach) and affiliative (Aff) needs. Results of story analyses revealed that achievement arousal increased scores of high Ach subjects and that high Aff subjects obtained higher scores than low Aff subjects. (BL)
Attitude Towards Physics and Additional Mathematics Achievement Towards Physics Achievement
ERIC Educational Resources Information Center
Veloo, Arsaythamby; Nor, Rahimah; Khalid, Rozalina
2015-01-01
The purpose of this research is to identify the difference in students' attitude towards Physics and Additional Mathematics achievement based on gender and relationship between attitudinal variables towards Physics and Additional Mathematics achievement with achievement in Physics. This research focused on six variables, which is attitude towards…
The Impact of Reading Achievement on Overall Academic Achievement
ERIC Educational Resources Information Center
Churchwell, Dawn Earheart
2009-01-01
This study examined the relationship between reading achievement and achievement in other subject areas. The purpose of this study was to determine if there was a correlation between reading scores as measured by the Standardized Test for the Assessment of Reading (STAR) and academic achievement in language arts, math, science, and social studies…
Approximated Stable Inversion for Nonlinear Systems with Nonhyperbolic Internal Dynamics. Revised
NASA Technical Reports Server (NTRS)
Devasia, Santosh
1999-01-01
A technique to achieve output tracking for nonminimum phase nonlinear systems with non- hyperbolic internal dynamics is presented. The present paper integrates stable inversion techniques (that achieve exact-tracking) with approximation techniques (that modify the internal dynamics) to circumvent the nonhyperbolicity of the internal dynamics - this nonhyperbolicity is an obstruction to applying presently available stable inversion techniques. The theory is developed for nonlinear systems and the method is applied to a two-cart with inverted-pendulum example.
Song, Jianxun; Wang, Qiuyu; Wu, Jinyu; Jiao, Shuqiang; Zhu, Hongmin
2016-08-15
KF is employed as a source of fluoride ions added to the melt to disclose the influence of fluoride on the disproportionation reactions of titanium ions, 3Ti(2+) = 2Ti(3+) + Ti, and 4Ti(3+) = 3Ti(4+) + Ti. The results reveal that the equilibrium transferred to the right direction for the first reaction and the apparent equilibrium constant increased sharply, mainly because of the formation of coordination compounds: TiFi(3-i). The accurate values of the equilibrium constants referring to the formation reactions of Ti(3+) + iF(-) = TiFi(3-i) (i = 1-6) in NaCl-KCl melt at 1023 K were evaluated with a best fit least squares method. It is also revealed that the stable states of the coordination compounds are TiF(2+), TiF2(+), TiF4(-) and TiF6(3-). Moreover, the Gibbs free energies for complex formation were estimated. Ti(2+) was undetectable when the concentration of fluoride ion was high enough. The equilibrium constant for the formation reaction, Ti(4-) + 6F(-) = TiF6(2-), was evaluated. The equilibrium constant, Kc2, for the disproportionation reaction 4Ti(3+) = 3Ti(4+) + Ti, in chloride melt was determined as 0.015.
Interactions of nanoparticles with proteins: determination of equilibrium constants.
Treuel, Lennart; Malissek, Marcelina
2013-01-01
The behavior of nanoparticles towards proteins is an important aspect across wide areas of nanotoxicology and nanomedicine. In this chapter, we describe a procedure to study the adsorption of proteins onto nanoparticle surfaces. Circular dichroism (CD) spectroscopy is utilized to quantify the amount of free protein in a solution, and the experimental information is evaluated to derive equilibrium constants for the protein adsorption/desorption equilibrium. These equilibrium constants are comparable parameters in describing the interactions between proteins and nanoparticles.
Roundabout relaxation: collective excitation requires a detour to equilibrium.
Morita, Hidetoshi; Kaneko, Kunihiko
2005-03-04
Relaxation to equilibrium after strong and collective excitation is studied by using a Hamiltonian dynamical system of a one-dimensional XY model. After an excitation of a domain of K elements, the excitation is concentrated to fewer elements, which are made farther away from equilibrium, and the excitation intensity increases logarithmically with K. Equilibrium is reached only after taking this roundabout route, with the time for relaxation diverging asymptotically as Kgamma with gamma approximately 4.2.