Mixture Of Condensates Research Articles

Effects of axial vorticity in elongated mixtures of Bose-Einstein condensates

We consider a meniscus between rotating and nonrotating species in the Bose-Einstein condensate with repulsive interatomic interactions, confined to a pipe-shaped trap. In this setting, we derive a system of coupled one-dimensional nonpolynomial Schr\"odinger equations for two mean-field wave functions. Using these equations, we analyze the phase separation and mixing in the pipe with periodic axial boundary conditions, i.e., in a toroidal configuration. We find that the onset of the mixing, in the form of suction, i.e., filling the empty core in the vortical component by its nonrotating counterpart, crucially depends on the vorticity of the first component and on the strengths of the interatomic interactions.

Temperature-driven collapse of a coherent binary mixture of condensates

We present a temperature-dependent Hartree-Fock-Bogoliubov-Popov theory to analyze the properties of the equilibrium states of an homogeneous mixture of bosonic atoms in two different hyperfine states and in the presence of an internal Josephson coupling. In our calculation we show that the bistable structure of the equilibrium states at zero temperature changes when we increase the temperature of the system. We investigate two mechanisms of the disappearance of bistability. In one, near the collapse of one of the equilibrium states, the acoustical branch becomes unstable and the gap of the optical branch goes to zero. In the other, there is no divergent behavior of the system and bistability disappears at a temperature in which the two equilibrium states merge at a zero-population fraction imbalance. When we further increase the temperature, this state remains as a unique equilibrium configuration.

Modification of Esmaeilzadeh–Roshanfekr equation of state to improve volumetric predictions of gas condensate reservoir

The Peneloux–Rauzy–Freze (PRF) method of improving volumetric predictions by introducing the volume shift into the equation of state, is applied to the Esmaeilzadeh–Roshanfekr equation of state (ER-EOS). The ER-EOS is a new three parameter equation of state that was developed in 2006 aiming to be applied to reservoir fluids. First, this equation of state was developed for pure hydrocarbons and then was extended to mixtures by using mixing rules [M. Bonyadi, F. Esmaeilzadeh, Fluid Phase Equilib. 260 (2007) 326–334]. The modified ER-EOS (mER-EOS) is expected to improve volumetric predictions of gas condensate by applying volume shift for heavy end(s). In this study, three gas condensate fluid samples taken from three wells in a real field in Iran, referred here as SA1, SA4 and SA8, as well as two samples from literature have been used to check the validity of the modified ER-EOS in calculating the PVT properties of gas condensate mixtures. Some experiments such as constant composition expansion (CCE), constant volume depletion (CVD) and dew point pressures are carried out on these samples. Relative volume and condensate drop-out in CCE and CVD tests were predicted by ER-EOS, mER-EOS, PR-EOS and SRK-EOS [D.Y. Peng, D.B. Robinson, Ind. Eng. Chem. Fundam. 15 (1), (1976) 59–64; G. Soave, Chem. Eng. Sci. 27 (1972) 1197–1203]. Comparison results between experimental and calculated data indicate that the mER-EOS has smaller error than the ER-EOS, PR-EOS and SRK-EOS. By this modification, the total average absolute deviations of the predicted liquid saturation from CVD experiments and relative volume from CCE experiments are 13.17% and 0.99%, respectively.

Localized modes of binary mixtures of Bose-Einstein condensates in nonlinear optical lattices

The properties of the localized states of a two-component Bose-Einstein condensate confined in a nonlinear periodic potential (nonlinear optical lattice) are investigated. We discuss the existence of different types of solitons and study their stability by means of analytical and numerical approaches. The symmetry properties of the localized states with respect to nonlinear optical lattices are also investigated. We show that nonlinear optical lattices allow the existence of bright soliton modes with equal symmetry in both components and bright localized modes of mixed symmetry type, as well as dark-bright bound states and bright modes on periodic backgrounds. In spite of the quasi-one-dimensional nature of the problem, the fundamental symmetric localized modes undergo a delocalizing transition when the strength of the nonlinear optical lattice is varied. This transition is associated with the existence of an unstable solution, which exhibits a shrinking (decaying) behavior for slightly overcritical (undercritical) variations in the number of atoms.

The self-similar problem of the diffusion mixing of vapour–gas–condensate systems

Self-similar solutions of the problem of the diffusion mixing of vapour–gas–condensate mixtures, which is a generalization of the Stefan problem, are constructed. It is established on the basis of the solution of the problem concerning the mixing a vapour with a gas that, depending on the initial temperatures, mixing can occur with the formation of an intermediate vapour–gas–condensate layer. A chart of the possible structures of the mixing zones of a vapour–gas–condensate system with a vapour-gas mixture is obtained.

Static and Dynamic Properties of Multicomponent Bose–Einstein Condensates of Ytterbium Atoms

We consider theoretically static and dynamic properties of multicomponent Bose–Einstein condensates (BECs) composed of a mixture of 174Yb and 176Yb atoms. The condensate of 176Yb atoms has an attractive interaction, collapsing above a certain critical particle number. This criterion is modified by the presence of another repulsive condensate of 174Yb atoms. We discuss the stability condition of this condensate mixture and collapsing dynamics due to the instability.

Prediction of gas condensate properties by Esmaeilzadeh–Roshanfekr equation of state

The Esmaeilzadeh–Roshanfekr (ER) equation of state (EOS) is used to predict the PVT properties of gas condensate reservoir fluids. Three gas condensate fluid samples taken from three wells in a real field in Iran, referred here as SA1, SA4 and SA8, as well as five samples from literature have been used to check the validity of the ER EOS in calculating the PVT properties of gas condensate mixtures. Some experiments such as constant composition expansion (CCE), constant volume depletion (CVD) and dew point pressures are carried out on these samples. In order to have an unbiased comparison between the ER and the Peng–Robinson (PR) equation of state, van der Waals mixing rules are used without using any adjustable parameters ( k ij = 0). Also, no pure component parameters are adjusted. The critical properties and acentric factor for plus-fraction are estimated by the Kesler–Lee, Pedersen et al. and Riazi–Daubert characterization methods. The results of dew point pressure calculations show that the ER EOS has smaller error than the PR EOS. For some mixtures, relative volume, gas compressibility factor and condensate drop-out in CVD and CCE test were also predicted. Comparison results between experimental and calculated data indicate that the ER EOS has smaller error than the PR EOS. The total average absolute deviation was found to be 0.82% and 2.97% for calculating gas compressibility factor and gas specific gravity in CVD test. Also, the total average absolute deviation was found to be 2.06% and 3.42% for calculating gas compressibility factor and relative volume in CCE test.

Mixed-symmetry localized modes and breathers in binary mixtures of Bose-Einstein condensates in optical lattices

We study localized modes in binary mixtures of Bose-Einstein condensates embedded in one-dimensional optical lattices. We report a diversity of asymmetric modes and investigate their dynamics. We concentrate on the cases where one of the components is dominant, i.e. has much larger number of atoms than the other one, and where both components have the numbers of atoms of the same order but different symmetries. In the first case we propose a method of systematic obtaining the modes, considering the "small" component as bifurcating from the continuum spectrum. A generalization of this approach combined with the use of the symmetry of the coupled Gross-Pitaevskii equations allows obtaining breather modes, which are also presented.

Half-Skyrmions and spike-vortex solutions of two-component nonlinear Schrödinger systems

Recently, Skyrmions with integer topological charges have been observed numerically but have not yet been shown rigorously on two-component systems of nonlinear Schrödinger equations (NLSEs) describing a binary mixture of Bose-Einstein condensates [see Battye et al., Phys. Rev. Lett. 88, 080401 (2002) and Savage and Ruostekoski, Phys. Rev. Lett. 91, 010403 (2003)] Besides, half-Skyrmions characterized by half-integer topological charges can also be found in the nonlinear σ model which is a model of the Bose-Einstein condensate of the Schwinger bosons [see Morinari, Phys. Rev. B 72, 104502 (2005)]. Here we prove rigorously the existence of half-Skyrmions which may come from a new type of soliton solutions called spike-vortex solutions of two-component systems of NLSE on the entire plane R2. These spike-vortex solutions having spikes in one component and a vortex in the other component may form half-Skyrmions. By Liapunov-Schmidt reduction process, we may find spike-vortex solutions of two-component systems of NLSE.

油井管材料の腐食挙動に及ぼすコンデンセート中の水分率の影響

In order to investigate corrosion behavior of representative Oil Country Tubular Goods (OCTG) materials in environments of gas condensate/water/CO2 or CO2+H2S, laboratory and field corrosion tests were carried out. The laboratory tests were carried out in CO2 or CO2+H2S environments by using an autoclave. Test specimens were set in liquid and gas phases of the autoclave and the water fraction ratio of condensate and water mixture was changed to study the effects of water fraction on corrosion behavior of OCTG materials in oil and gas well environment. In the filed tests, Down hole coupon (DHC) tests were carried out in a sour gas well in the United Arab Emirates. The DHC tests were performed at three different well depths with different water fraction. The laboratory liquid phase test results indicated that corrosion occurs by water wetting on material after emulsion break. The laboratory gas phase test results show that the vapor of condensate acts as corrosion barrier. The comparison between the laboratory and the field tests results indicates that localized corrosion occurred on carbon steel in the field test but did not occur in the laboratory gas phase test, although corrosion rate in the field test was almost the same as that in the laboratory gas phase test. This is because localized water wet condition could not be reproduced in the laboratory gas phase test. From these results, tubing material used for gas well should be selected with taking account of localized water wet conditions, even if a water fraction of bulk fluid is significantly low.

New Class of "Green" Corrosion Inhibitors: Development and Application

This article, written by Technology Editor Dennis Denney, contains highlights of paper SPE 104241, "A New Class of ‘Green’ Corrosion Inhibitors: Development and Application," by H.A. Craddock, SPE, S. Caird, and H. Wilkinson, Roemex Ltd., and M. Guzmann, BASF, prepared for the 2006 SPE International Oilfield Corrosion Symposium, Aberdeen, 30 May. Use of chemical corrosion inhibitors is common in production and processing operations. Particularly challenging is the development of new chemistries, which maintain good protection of materials under a variety of conditions while being environmentally acceptable. This paper illustrates patented work in the chemistry of Alkylpolyglucosides (APGs) and their synergistic effect with polyaspartates. This inhibitor class demonstrated good general inhibitor performance in several oilfield brines, showed good filming characteristics under conditions of shear, and provided an excellent environmental profile. Introduction Chemical inhibitors play an important role in the protection and mitigation strategies for retarding corrosion. Several chemistries have been successful, primarily amines, quaternary salts of amines, and imidazolines, all of which act as filming protection agents either filming on the metal surface or on a variety of scales (e.g., calcium carbonate) deposited on these surfaces. In addition to filming characteristics, corrosion inhibitors must slow the corrosion rate, usually by a combination of increasing the anodic or cathodic polarization behavior, reducing the movement or diffusion of ions to the metal surface, and increasing the electrical resistance of the metal surface. The mixture of crude oil, condensate, and connate and other waters (brines) can result in highly aggressive and corrosive media in contact with carbon steel. To challenge this environment further, these mixtures often are under high-flow-rate conditions, creating several shear-stress conditions. Traditionally, chemical corrosion inhibitors needed the ability to film, within fluid mixtures, at the surface between liquid and solid (i.e., surfactant like materials) and needed resistance to removal under high-flow-rate conditions. In general, these materials are excellent corrosion inhibitors under a variety of field conditions. However, they do have performance boundaries, such as high temperature, and have properties relating to marine toxicity and biodegradation that make them less acceptable for use in highly regulated offshore environments such as the North Sea and north east Atlantic. Producing more-acceptable environmental profiles for inhibitor properties could compromise the desired technical effects (e.g., persistent materials usually are not readily biodegradable). Similarly, several chemistries are nitrogen based and possess inherent toxic properties. Faced with this challenge, various strategies were studied to reduce environmental effects while maintaining desired surfactant properties and persistency (e.g., amino acid, aspartic acid, and polyaspartates). However, these chemistries require high dosage rates or have insufficient biodegradation to meet the required environmental regulations. Earlier works showed that agents other than filming surfactants could provide good corrosion protection under high-flow-rate conditions. However, the chemistry did not provide complete answers to biodegradation problems. It was found that, under certain conditions, APGs can provide good filming and protective characteristics and an excellent environmental profile without losing significant persistency.

Phase Textures Induced by dc-Current Pair Breaking in Weakly Coupled Multilayer Structures and Two-Gap Superconductors

We predict the current-induced formation of equilibrium phase textures for a multicomponent superconducting order parameter. Using the two-component Ginzburg-Landau and Usadel equations, we show that, for weakly coupled comoving superconducting condensates, the dc current I first causes the breakdown of the phase-locked state at I>I{c1} followed by the formation of intrinsic phase textures well below the depairing current I{d}. These phase textures can manifest themselves in multilayer structures, atomic Bose condensate mixtures in optical lattices, and two-gap superconductors, particularly MgB(2), where they can result in oscillating and resistive switching effects.

Calculation of minimum miscibility pressure for gas condensate reservoirs

This work focuses on analytical calculation of MMP for gas condensate reservoirs. For the sake of simplicity, the method outlined by Wang [Y. Wang, Doctoral Dissertation, Stanford University, USA, 1998] and pseudo-components are used for calculating MMP. We evaluated this method using the Peng–Robinson EOS, Patel–Teja EOS, Patel–Teja–Valderrama EOS, and the Esmaeilzadeh–Roshanfekr EOS and compared it with the experimental data. The agreement between calculated MMPs and the experimental data confirm the validity of the model. Once the validity is checked, the MMP is calculated for condensates and injection gases containing CO 2 and NGL fractions. The condensate and injection gas mixtures were selected from a gas field in Iran here referred to as SGF.

Incompressible and Compressible Limits of Coupled Systems of Nonlinear Schrödinger Equations

Recently, coupled systems of nonlinear Schrodinger equations have been used extensively to describe a double condensate, i.e. a binary mixture of Bose-Einstein condensates. In a double condensate, an interface and shock waves may occur due to large intraspecies and interspecies scattering lengths. To know the dynamics of an interface and assure the existence of shock waves in a double condensate, we study the incompressible and the compressible limits respectively of two coupled systems of nonlinear Schrodinger equations. The main idea of our arguments is to define a “H-functional” like a Lyapunov functional which can control the propagation of densities and linear momenta. Such an idea is different from the one using the standard Wigner transform to investigate the incompressible and the compressible limits of a single nonlinear Schrodinger equation. \(\mathfrak{V}\)

Transport Properties of Condensable and Non-condensable Gas Mixtures through Microporous Silica Membranes Studied with Molecular Dynamics Simulation

溶融–急冷法によって作製した仮想アモルファスシリカ膜のサブナノ細孔における凝縮性気体および凝縮性／非凝縮性気体混合物の透過シミュレーションを非平衡分子動力学法を用いて行った．直径約8 Åの細孔におけるエタン状LJ粒子の透過特性に関しては，400 Kから800 Kの比較的高温域において表面拡散的傾向が見られ，室温付近においては透過速度は温度の低下に伴って減少した．細孔表面との親和性がエタンに比べて小さい非凝縮性気体である窒素状LJ粒子の透過速度はエタンよりも小さく，高温域から室温に至る温度範囲で表面拡散的な透過傾向が見られた．実際のエタンの臨界温度（TC）よりも低い温度である260 Kにおけるエタン／窒素混合気体の透過シミュレーションでは，比較的エタン分率（分圧）が小さい条件ではエタンの透過速度に大きな分圧依存性は見られなかったが，ある分圧を越えると透過速度は大きく減少した．混合系における窒素の透過速度はエタン分圧が小さいところでエタン分圧の増加に伴って減少し，すべての分圧下において純窒素透過シミュレーション時の透過速度よりも小さかった．これらの結果は，細孔表面と大きな親和性を有する凝縮性気体によって非凝縮性気体の移動が阻害され透過速度が低下することを示している．また，臨界温度以下の温度のある圧力下において形成されるミクロ孔充填相は，凝縮性気体自身の透過性も低下させると考えられる．サブナノ細孔における凝縮性気体の透過・分離特性にミクロ孔充填相の形成が重要な役割を果たしていることが分子シミュレーションにより明らかとなった．

Sympathetic cooling route to Bose-Einstein condensate and Fermi-liquid mixtures

We discuss a sympathetic cooling strategy that can successfully mitigate fermion-hole heating in a dilute atomic Fermi-Bose mixture and access the temperature regime in which the fermions behave as a Fermi liquid. We introduce an energy-based formalism to describe the temperature dynamics with which we study a specific and promising mixture, composed of $^{6}\mathrm{Li}$ and $^{87}\mathrm{Rb}$. Analyzing the harmonically trapped mixture, we find that the favorable features of this mixture are further enhanced by using different trapping frequencies for the two species.

Vortices in condensate mixtures

In a condensate made of two different atomic molecular species, Onsager's quantization condition implies that around a vortex the velocity field cannot be the same for the two species. We explore some simple consequences of this observation. Thus if the two condensates are in slow relative translation one over the other, the composite vortices are carried at a velocity that is a fraction of the single species velocity. This property is valid for attractive interaction and below a critical velocity which corresponds to a saddle-node bifurcation.

Field- and temperature-induced topological phase transitions in the three-dimensionalN-component London superconductor

The phase diagram and critical properties of the $N$-component London superconductor are studied both analytically and through large-scale Monte Carlo simulations in $d=2+1$ dimensions (components here refer to different replicas of the complex scalar field). Examples are given of physical systems to which this model is applicable. The model with different bare phase stiffnesses for each component is a model of superconductivity, which should arise out of metallic phases of light atoms under extreme pressure. A projected mixture of electronic and protonic condensates in liquid metallic hydrogen under extreme pressure is the simplest example, corresponding to $N=2$. These are such that Josephson coupling between different matter field components is precisely zero on symmetry grounds. The $N$-component London model is dualized to a theory involving $N$ vortex fields with highly nontrivial interactions. We compute critical exponents $\ensuremath{\alpha}$ and $\ensuremath{\nu}$ for $N=2$ and $N=3$. Direct and dual gauge field correlators for general $N$ are given and the $N=2$ case is studied in detail. The model with $N=2$ shows two anomalies in the specific heat when the bare phase stiffnesses of each matter field species are different. One anomaly corresponds to an inverted $3\mathrm{D}xy$ fixed point, while the other corresponds to a $3\mathrm{D}xy$ fixed point. Correspondingly, for $N=3$, we demonstrate the existence of two neutral $3\mathrm{D}xy$ fixed points and one inverted charged $3\mathrm{D}xy$ fixed point. For the general case, there are $N$ fixed points, namely one charged inverted $3\mathrm{D}xy$ fixed point, and $N\ensuremath{-}1$ neutral $3\mathrm{D}xy$ fixed points. We explicitly identify one charged vortex mode and $N\ensuremath{-}1$ neutral vortex modes. The model for $N=2$ and equal bare phase stiffnesses corresponds to a field theoretical description of an easy-plane quantum antiferromagnet. In this case, the critical exponents are computed and found to be non-$3\mathrm{D}xy$ values. The $N$-component London superconductor model in an external magnetic field, with no interspecies Josephson coupling, will be shown to have a different feature, namely $N\ensuremath{-}1$ superfluid phases arising out of $N$ charged condensates. In particular, for $N=2$ we point out the possibility of two different types of field-induced phase transitions in ordered quantum fluids: (i) A phase transition from a superconductor to a superfluid or vice versa, driven by tuning an external magnetic field. This sets the superconducting phase of liquid metallic hydrogen apart from other known quantum fluids. (ii) A phase transition corresponding to a quantum fluid analogue of sublattice melting, where a composite field-induced Abrikosov vortex lattice is decomposed and disorders the phases of the constituent condensate with lowest bare phase stiffness. Both transitions belong to the $3\mathrm{D}xy$ universality class. For $N\ensuremath{\geqslant}3$, there is a feature not present in the cases $N=1$ and $N=2$, namely a partial decomposition of composite field-induced vortices driven by thermal fluctuations. A ``color electric charge'' concept, useful for establishing the character of these phase transitions, is introduced.

Antimicrobial effect of lactic acid producing bacteria culture condensate mixture (LCCM) against Salmonella enteritidis

The antimicrobial effects of a lactic acid producing bacteria culture condensate mixture (LCCM) were assessed against Salmonella enteritidis. In the presence of LCCM, bacterial growth was assessed in vitro by the measurement of optical density (OD) and viable bacterial counting. At concentrations of 1.25 and 2.5% LCCM, OD values were significantly lower than that of the control broth, and at concentrations of 5 and 10% LCCM, OD values did not increase for the entire period of experiment. At 8 h after incubation, the viable bacterial numbers in 5% and 10% LCCM-containing broths were remarkably lower than that in the control broth. This antimicrobial ability of the LCCM was fundamentally attributed to causing cell death rather than inhibiting growth. Even when the pH of LCCM-containing broth was adjusted to 7.2, the number of viable bacteria was significantly lower in the broths containing LCCM over 2.5% than that in control broth at 8 h after incubation. However, the OD value of each culture in the presence of each concentration of the LCCM increased over 1.0 at the completion of the experiment. The in vivo antimicrobial effects of the LCCM against S. enteritidis were also assessed. In S. enteritidis-infected mice, the LCCM decreased both the viable bacteria found in the feces and the mortality rate of the mice. These findings showed that the LCCM might have an antimicrobial ability against S. enteritidis.

Optimization of the composition of oil and gas condensate mixtures for primary refining

A simple method of calculating the optimum composition of oil and gas condensate feedstock with the easily determined physicochemical properties of its components and standardized performance properties of petroleum products is examined.