One-dimensional Gas Research Articles

High fidelity control of a many-body Tonks-Girardeau gas with an effective mean-field approach

Shortcuts to adiabaticity (STA) are powerful tools that can be used to control quantum systems with high fidelity. They work particularly well for single particle and noninteracting systems which can be described exactly and which possess invariant or self-similar dynamics. However, finding an exact STA for strongly correlated many-body systems can be difficult, as their complex dynamics may not be easily described, especially for larger systems that do not possess self-similar solutions. Here, we design STAs for one-dimensional bosonic gas in the Tonks-Girardeau limit by using a mean-field approach that succinctly captures the strong interaction effects through a quintic nonlinear term in the Schrödinger equation. We show that for the case of the harmonic oscillator with a time-dependent trap frequency the mean-field approach works exactly and recovers the well-known STA from literature. To highlight the robustness of our approach we also show that it works effectively for anharmonic potentials, achieving higher fidelities than other typical control techniques. Published by the American Physical Society 2024

Experimental Study on the Effect of Mixed Thermodynamic Inhibitors with Different Concentrations on Natural Gas Hydrate Synthesis

Natural gas hydrate (NGH) is a potential future energy resource. More than 90% of NGH resources exist in the pore medium of seafloor sediments. During the development of deep-sea oil and gas fields, wellbore pipelines are often clogged due to the synthesis of gas hydrates, and the addition of thermodynamic inhibitors is a common solution to prevent hydrate synthesis. In this paper, the effects of two single inhibitors, sodium chloride and ethylene glycol, as well as hybrid inhibitors combining these two inhibitors on the synthesis of methane hydrates were investigated using the self-developed one-dimensional gas hydrate exploitation simulation test apparatus. The effects of single and hybrid inhibitors were investigated in terms of the hydrate synthesis volume and gas–water two-phase conversion rate. The results show that the hybrid inhibitor has a better inhibitory effect on hydrate synthesis with the same initial synthesis driving force. When the concentration of inhibitors is low, salt inhibitors can have a better inhibitory effect than alcohol inhibitors. However, in the mixed inhibitor experiment, increasing the proportion of ethylene glycol in the mixed inhibitor can more effectively inhibit the synthesis of hydrates than increasing the proportion of sodium chloride in the mixed inhibitor.

Numerical study on effect of operating pressures on CRKEC-based two-stage ejector

The two-stage ejector mixing-diffuser section in this study was computed using the Redlich-Kwong equation of state. The ejector was designed based on the constant rate of kinetic energy change (CRKEC) approach. The water vapor mixing diffuser profile and flow properties were calculated using a one-dimensional gas dynamic model. For the numerical investigation, the estimated geometrical profile based on the input design and operating conditions was utilized. ANSYS-Fluent 14.0 was em-ployed for the numerical study. The analysis was conducted under both on-design and off-design scenarios using the standard k-ε turbulence model. The impact of operating factors on flow behavior and entrainment ratios was investigated at off-design conditions. The findings demonstrated that the operational total pressures of the primary, secondary, and exit flows are a function of the two-stage ejector (TSE) entrainment ratio. With a higher exit pressure and more secondary/entrained flows, the entrain-ment ratio increases. However, altering the primary flow pressure in ways other than for the design conditions reduces the entrainment ratio.

Non-Hermitian p -wave superfluid and effects of the inelastic three-body loss in a one-dimensional spin-polarized Fermi gas

We theoretically investigate non-Hermitian p-wave Fermi superfluidity in one-dimensional spin-polarized Fermi gases which is relevant to recent ultracold atomic experiments. Considering an imaginary atom-dimer coupling responsible for the three-body recombination process in the Lindblad formalism, we discuss the stability of the superfluid state against the atomic loss effect. Within the two-channel non-Hermitian BCS-Eagles-Leggett theory, the atomic loss is characterized by the product of the imaginary atom-dimer coupling and the p-wave effective range. Our results indicate that for a given imaginary atom-dimer coupling, a smaller magnitude of the effective ranges of p-wave interaction is crucial for reaching the non-Hermitian p-wave Fermi superfluid state. Moreover, our theoretical framework for many-body systems with the three-body loss, which is inevitable in ultracold atoms, would promote further progress in non-Hermitian cold-atomic physics. Published by the American Physical Society 2024

Identification of Bis(methylsulfanyl)methane and Furan-2(5H)-one as Volatile Marker Compounds for the Differentiation of the White Truffle Species Tuber magnatum and Tuber borchii.

Some truffles are expensive and, therefore, are prone to food fraud. A particular problem is the differentiation of high-priced Tuber magnatum truffles from cheaper Tuber borchii truffles, both of which are white truffles with similar morphological characteristics. Using an untargeted approach, the volatiles isolated from samples of both species were screened for potential marker compounds by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-TOFMS) and statistical analysis of the obtained semiquantitative data. Results suggested bis(methylsulfanyl)methane and furan-2(5H)-one as compounds characterizing T. magnatum and T. borchii, respectively. Exact quantitation of both volatiles by conventional one-dimensional gas chromatography-mass spectrometry in combination with stable isotopologues of the target compounds as internal standards confirmed both as marker compounds. The method is suitable to be used in the routine analysis for the objective species differentiation of T. magnatum and T. borchii.

One-dimensional temperature measurement of gases based on femtosecond laser-extended electrode discharge spectroscopy (FEEDS)

Temperature, and hence thermometry techniques, are critical for characterizing gaseous flows and flames. Therefore, it is always attractive to develop new thermometry techniques to satisfy different demands. Here, we propose a thermometry technique for one-dimensional gas temperature measurements based on femtosecond laser-extended electrode discharge spectroscopy (FEEDS). By FEEDS measurements in gas flows containing hydrogen, we found that the temperature of the gas flow has a strong correlation with the full width at half maximum (FWHM) of the atomic hydrogen line at 656 nm, and this correlation is monotonic in the temperature range we measured, i.e., the temperature of gas flows can be extracted by measuring this FWHM. We applied this technique to methane/air gas mixtures and realized temperature measurements in the range of 300–1806 K with an error of ∼50 K. Also, we found that the technique has the capability to achieve one-dimensional measurements; more importantly, we found that changes in the stoichiometric ratio of the gas mixture do not affect the temperature measurements. Finally, we applied this technique to a premixed methane/air jet flame.

Deep Learning for Gas Sensing via Infrared Spectroscopy.

Deep learning methods, a powerful form of artificial intelligence, have been applied in a number of spectroscopy and gas sensing applications. However, the speciation of multi-component gas mixtures from infrared (IR) absorption spectra using deep learning remains to be explored. Here, we propose a one-dimensional deep convolutional neural network gas classification model for the identification of small molecules of interest based on IR absorption spectra in flexible user-defined frequency ranges. The molecules considered include ten that are of interest in the atmosphere or in industrial and environmental processes: water vapor, carbon dioxide, ozone, nitrous oxide, carbon monoxide, methane, nitric oxide, sulfur dioxide, nitrogen dioxide, and ammonia. A simulated dataset of IR absorption spectra for mixtures of these molecules diluted in air was generated and used to train a deep learning model. The model was tested against simulated spectra containing noise and was found to provide speciation predictions with accuracy from 82 to 97%. The internal operation of the model was investigated using class activation maps that illustrate how the model prioritizes spectral information for classification. Finally, the model was demonstrated for the prediction of speciation for two synthetic experimental mixture spectra. The proposed model and the dataset generation strategies are generalized and can be implemented for other gases, different frequency ranges, and spectroscopy types. The multi-component speciation method developed herein is the first application of a convolutional neural network model, trained on HITRAN-based simulations, for spectral identification.

Effects of atom losses on a one-dimensional lattice gas of hard-core bosons

Effects of atom losses on a one-dimensional lattice gas of hard-core bosons

Ambipolar Diffusion with a Polytropic Equation of State

Ambipolar diffusion is the mechanism believed to be responsible for the loss of magnetic support in dense molecular cloud cores, and is therefore likely to play a key role in the star formation process. As such, this mechanism has been studied extensively both semianalytically and numerically. We build upon this existing body of work by considering a one-dimensional self-gravitating gas with a polytropic equation of state (P ∝ ρ ϵ ), and consider cases that range from softer (ϵ < 1) to stiffer (ϵ > 1) than isothermal. Our results indicate that the diffusion time is not very sensitive to the polytropic exponent ϵ when stiffer than isothermal, but is sensitive to the exponent when softer than isothermal. Additionally, the presence of magnetic and density fluctuations causes the ambipolar diffusion process to speed up, with the shortest diffusion times obtained for gases with large initial magnetic to gas pressure ratios and fairly soft equations of state. However, the diffusion time starts to increase significantly for ϵ ≲ 0.5, indicating that such soft equations of state are inconsistent with observations.

Initial-Boundary Value Problems for One-Dimensional pth Power Viscous Reactive Gas with Density-Dependent Viscosity

Initial-Boundary Value Problems for One-Dimensional pth Power Viscous Reactive Gas with Density-Dependent Viscosity

Atomic-Scale Time-Resolved Imaging of Krypton Dimers, Chains and Transition to a One-Dimensional Gas.

Single-atom dynamics of noble-gas elements have been investigated using time-resolved transmission electron microscopy (TEM), with direct observation providing for a deeper understanding of chemical bonding, reactivity, and states of matter at the nanoscale. We report on a nanoscale system consisting of endohedral fullerenes encapsulated within single-walled carbon nanotubes ((Kr@C60)@SWCNT), capable of the delivery and release of krypton atoms on-demand, via coalescence of host fullerene cages under the action of the electron beam (in situ) or heat (ex situ). The state and dynamics of Kr atoms were investigated by energy dispersive X-ray spectroscopy (EDS), electron energy loss spectroscopy (EELS), and X-ray photoelectron spectroscopy (XPS). Kr atom positions were measured precisely using aberration-corrected high-resolution TEM (AC-HRTEM), aberration-corrected scanning TEM (AC-STEM), and single-atom spectroscopic imaging (STEM-EELS). The electron beam drove the formation of 2Kr@C120 capsules, in which van der Waals Kr2 and transient covalent [Kr2]+ bonding states were identified. Thermal coalescence led to the formation of longer coalesced nested nanotubes containing more loosely bound Krn chains (n = 3-6). In some instances, delocalization of Kr atomic positions was confirmed by STEM analysis as the transition to a one-dimensional (1D) gas, as Kr atoms were constrained to only one degree of translational freedom within long, well-annealed, nested nanotubes. Such nested nanotube structures were investigated by Raman spectroscopy. This material represents a highly compressed and dimensionally constrained 1D gas stable under ambient conditions. Direct atomic-scale imaging has revealed elusive bonding states and a previously unseen 1D gaseous state of matter of this noble gas element, demonstrating TEM to be a powerful tool in the discovery of chemistry at the single-atom level.

Influence of depressurization mode on natural gas hydrate production characteristics: One-dimensional experimental study

The latest research suggests that using depressurization methods and their enhancements could be the most effective way to produce natural gas hydrates efficiently in marine areas. Therefore, it's crucial to investigate the gas production behavior and the changes in temperature and pressure within natural gas hydrate reservoirs under different depressurization methods. In this paper, the self-developed one-dimensional natural gas hydrate production simulation test system was utilized to conduct one-dimensional depressurization production tests during two depressurization modes of significant depressurization and slow depressurization. The findings indicated that the minimum temperature increment-depressurization rate curves in significant depressurization tests exhibited irregular patterns, primarily due to the frequency and intensity of hydrate reformation, while the smaller the depressurization rate, the larger the minimum temperature increment and the smaller the maximum dissociation rate under slow depressurization. In addition, when maintaining a fixed hydrate saturation level, the peak gas production rate showed a decline with decreasing depressurization rate. However, the exact correlation between the peak gas production rate and the depressurization rate remained uncertain due to the unpredictable nature of the “armoring” effect.

Численное решение системы уравнений Навье–Стокса в случае сжимаемой среды с использованием нейронных сетей

The use of the Physics Informed Neural Networks (PINN) method for the numerical solution of a nonstationary nonlinear system of partial differential equations describing the process of motion of a one-dimensional heat-conducting gas is considered. The approach is based on the fact that a neural network approximates the solution of a system of differential equations, while taking into account the physics of the simulated process. The neural network is trained by minimizing a quadratic functional built on the difference between the predicted values and residuals of differential equations, boundary and initial conditions. Different types of approximation of the original equations are discussed in the case when the operator is continuous or discrete in time. An analysis of the presented methods is carried out. Their advantages and disadvantages are indicated.

Exploring the untargeted metabolites of Moringa oleifera Lam seed oil using two-dimensional gas chromatography with time of flight mass spectrometry for therapeutic application

Moringa oleifera Lam is an economically and medicinally important plant. However, its essential oil characterization has been limited to one-dimensional gas chromatography and mass spectrometry. This study identified secondary metabolite composition and variation in M. oleifera seed oil through two-dimensional gas chromatography with time of flight mass spectrometry and their associated bioactivity. GC×GC TOF MS analysis of M. oleifera seed oil was performed on an Agilent 7890 Gas chromatograph equipped with Pegasus 2D GC-TOFMS. About 1µl of the sample (dissolved in n-Hexane) was injected into the system, and the carrier gas was Helium. Identification was made using ChromaTOF software with reference to the NIST library. A total of 2000 phytoconstituents were obtained, of which 236 were identified using the NIST mass spectral values. Total constituents were classified into alkanes (64), alkenes (11), aldehydes (7), alcohol (10), acids (18), acid esters (70), Ketones (10), benzenoids (10), Monoterpenoids (1), olefins (6), Phenols (1), an alkaloid (1), triterpenoid (4), diterpenoid (1), sesquiterpenoid (2), tocopherol (2), and Others (18). Based on area percentage, fatty acids and their derivatives were predominant. The major constituents were Erucic acid (9.10%), trans-13-Octadecenoic acid (6.06%), Triethyl citrate (5.15%), Bis-(3,5,5-trimethylhexyl) phthalate (4.94%). This study reports a detailed metabolic profiling of M. oleifera seeds, which opens up the possibility of identifying and decoding specific bioactivities leading to novel drug discovery in the future.

Friedel Oscillations in a One-dimensional Non-interacting Electron Gas in the Presence of Two Impuritites

Using the linear response theory, we analyze Friedel oscillations in a one-dimensional non-interacting electron gas in the presence of two impurities with different potential strengths. The impurities potentials are modeled using Dirac delta function, as well as Lorentzian and Gaussian distribution functions. Our findings show that density oscillations are strongly sensitive to both the distance between the impurities and their respective potential strengths. Keywords: one-dimensional electron gas, one impurity, two impurities, Friedel oscillations.

Unusual ergodic and chaotic properties of trapped hard rods.

We investigate ergodicity, chaos, and thermalization for a one-dimensional classical gas of hard rods confined to an external quadratic or quartic trap, which breaks microscopic integrability. To quantify the strength of chaos in this system, we compute its maximal Lyapunov exponent numerically. The approach to thermal equilibrium is studied by considering the time evolution of particle position and velocity distributions and comparing the late-time profiles with the Gibbs state. Remarkably, we find that quadratically trapped hard rods are highly nonergodic and do not resemble a Gibbs state even at extremely long times, despite compelling evidence of chaos for four or more rods. On the other hand, our numerical results reveal that hard rods in a quartic trap exhibit both chaos and thermalization, and equilibrate to a Gibbs state as expected for a nonintegrable many-body system.

H i in Molecular Clouds: Irradiation by FUV Plus Cosmic Rays

We extend the analytic theory presented by Sternberg et al. and Bialy & Sternberg for the production of atomic hydrogen (H i) via far-ultraviolet (FUV) photodissociation at the boundaries of dense interstellar molecular (H2) clouds to also include the effects of penetrating (low-energy) cosmic rays (CRs) for the growth of the total H i column densities. We compute the steady-state abundances of the H i and H2 in one-dimensional gas slabs in which the FUV photodissociation rates are reduced by depth-dependent H2 self-shielding and dust absorption and the CR ionization rates are either constant or reduced by transport effects. The solutions for the H i and H2 density profiles and the integrated H i columns depend primarily on the ratios I UV/Rn and ζ/Rn, where I UV is the intensity of the photodissociating FUV field, ζ is the H2 CR ionization rate, n is the hydrogen gas density, and R is the dust surface H2 formation rate coefficient. We present computations for a wide range of FUV field strengths, CR ionization rates, and dust-to-gas ratios. We develop analytic expressions for the growth of the H i column densities. For Galactic giant molecular clouds (GMCs) with multiphased (warm/cold) H i envelopes, the interior CR zones will dominate the production of the H i only if s−1, where M GMC is the GMC mass, and including attenuation of the CR fluxes. For most Galactic GMCs and conditions, FUV photodissociation dominates over CR ionization for the production of the H i column densities. Furthermore, the CRs do not affect the H i-to-H2 transition points.

Analytical Solution of Mixed Problems for the One-Dimensional Ionization Equations in the Case of Constant Velocities of Atoms and Ions

We consider the main initial–boundary value (mixed) problems for the nonlinear system of one-dimensional gas ionization equations in the case of constant velocities of gas atoms and ions resulting from ionization. The atom and ion concentrations are the unknowns in this system. We find a general formula for a sufficiently smooth solution of the system. It is shown that mixed problems for the system of one-dimensional ionization equations admit integration in closed-form analytical expressions. In the case of a mixed problem for a finite interval, the analytical solution is constructed using recurrence formulas each of which is defined in a triangle belonging to some triangulation, specified in the paper, of the domain where the unknown functions are defined.

Calculation of Electrophysical Characteristics of Semiconductor Quantum Wire Device Structures with One-Dimensional Electron Gas

Calculation of Electrophysical Characteristics of Semiconductor Quantum Wire Device Structures with One-Dimensional Electron Gas

Comprehensive characterization of speciated volatile organic compounds (VOCs), gas-phase and particle-phase intermediate- and semi-volatile volatility organic compounds (I/S-VOCs) from Chinese diesel trucks

We established the comprehensive emission profiles of organic compounds for typical Chinese diesel trucks. The profiles cover the entire volatility range, including speciated volatile organic compounds (VOCs), intermediate-volatility organic compounds (IVOCs), and semi-volatile organic compounds (SVOCs). The VOCs and I/SVOCs were analyzed by one-dimensional gas chromatography quadrupole mass spectrometry (GC qMS) and two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-ToF-MS) separately. The impacts of starting mode and aftertreatment technology on the VOC, gaseous and particulate I/SVOC emissions, and the gas-particle partitioning were investigated. The emission factor (EF) of gas phase I/SVOCs was approximately 10 times higher than that of particle phase I/SVOCs and the chemical compositions and volatility distributions varied greatly. VOC, IVOC, and SVOC emissions significantly decreased when vehicles were equipped with advanced aftertreatment technologies. Diesel particulate filters (DPF) can remove >71 % VOC, 74 % gaseous, and 88 % particulate I/SVOCs, many of which are significant secondary organic aerosol (SOA) precursors. The chemical compositions and volatility distributions of the gaseous I/SVOCs and unburned diesel fuel were similar, revealing that diesel fuel is the main origin of the gaseous I/SVOCs. The I/SVOC emission profiles covering the whole volatility range, i.e., log10C* = −3 to 10 (C*: effective saturation concentration, μg m−3) were established.