233 research outputs found

    Long-time nonlinear dynamical evolution for P-band ultracold atoms in an optical lattice

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    We report the long-time nonlinear dynamical evolution of ultracold atomic gases in the P-band of an optical lattice. A Bose-Einstein condensate (BEC) is fast and efficiently loaded into the Pband at zero quasi-momentum with a non-adiabatic shortcut method. For the first one and half milliseconds, these momentum states undergo oscillations due to coherent superposition of different bands, which are followed by oscillations up to 60ms of a much longer period. Our analysis shows the dephasing from the nonlinear interaction is very conducive to the long-period oscillations induced by the variable force due to the harmonic confinement.Comment: 8 pages, 7 figure

    Behavior and Modeling of Circular Large Rupture Strain FRP-Confined Ice under Axial Compression

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    The application of concrete is severely limited in construction in cold areas. However, the local ice has functioned as a potential substitute for concrete for a long time. In order to make efficient use of ice to overcome its weaknesses of low strength and poor ductility, an innovative type of ice-filled large rupture strain (LRS) fiber-reinforced polymer (FRP) tube column was developed. The system consists of external LRS FRP tubes filled with plain ice or sawdust-reinforced ice. This paper presents an experimental investigation into the axial compressive behavior of such composite stub columns with circular sections. The test results confirmed that the axial compressive behavior of the ice cores was greatly improved because of the LRS FRP confinement, as well as the addition of sawdust in ice. The axial stress–strain curves of the LRS FRP-confined ice exhibited monotonically ascending bilinear shapes. Both the compressive strength and the ultimate axial strain of the confined ice were significantly enhanced with an increase of the thickness of the LRS FRP tube. A theoretical model for the LRS FRP-confined ice is proposed, in which the dilation properties (i.e., lateral strain–axial strain relation), as well as the entire axial stress–strain responses of the inner ice cores, are explicitly modeled with reasonable accuracy

    Semantic Similarity to Known Second Language Words Impacts Learning of New Meanings

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    Second language (L2) learners need to continually learn new L2 words as well as additional meanings of previously learned L2 words. The present study investigated the influence of semantic similarity on the growth curve of learning of artificially paired new meanings of previously known L2 words in Chinese–English bilinguals. The results of a translation recognition task showed that related meanings are learned faster and more accurately than unrelated meanings. The advantage of learning related new meaning persisted and increased for a week after learning the new meanings. These results suggest that semantic similarities impact the learning of new meanings for known L2 words, and that the shared features between previously known and new meanings of a word facilitate the process of incorporating the related new meaning into the lexical semantic network. Our results are discussed under the framework of the connectionist model

    Effects of aroma quality on the biotransformation of natural 2-phenylethanol produced using ascorbic acid

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    Background: Natural 2-phenylethanol (2-PE) is an important flavoring that emits the aroma of roses. During biotransformation, the aroma quality of natural 2-PE is affected by its main by-products, which include butanol, isobutyric acid, butyric acid, and isovaleric acid. Thus, controlling undesirable by-product formation can reduce the effect of odor on 2-PE aroma quality. Results: 2-PE was produced through biotransformation using L-phenylalanine as a substrate and glucose as a carbon source. Ascorbic acid was added to the system to improve the redox reaction and suppress the generation of by-products. Principal component analysis of the aroma quality of 2-PE was performed using an electronic nose. Similarity analysis revealed that the effects of four by-products on 2-PE aroma quality may be ranked in the following order: isovaleric acid < butyric acid < isobutyric acid < butanol. The sample that exhibited the best similarity to the standard 2-PE sample (99.19%) was the sample to which ascorbic acid had been added during glucose metabolism. Conclusions: 2-PE produced through the addition of ascorbic acid exhibited the closest aroma similarity to the standard 2-PE sample

    A Parameter Estimation Method for Nonlinear Systems Based on Improved Boundary Chicken Swarm Optimization

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    Parameter estimation is an important problem in nonlinear system modeling and control. Through constructing an appropriate fitness function, parameter estimation of system could be converted to a multidimensional parameter optimization problem. As a novel swarm intelligence algorithm, chicken swarm optimization (CSO) has attracted much attention owing to its good global convergence and robustness. In this paper, a method based on improved boundary chicken swarm optimization (IBCSO) is proposed for parameter estimation of nonlinear systems, demonstrated and tested by Lorenz system and a coupling motor system. Furthermore, we have analyzed the influence of time series on the estimation accuracy. Computer simulation results show it is feasible and with desirable performance for parameter estimation of nonlinear systems

    A study of starch resources with high-amylose content from five Chinese mutant banana species

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    Investigation on staple crop starch of new species has been becoming the research focus of scholars at present. Based on this, the physicochemical properties and microstructural characteristics of starches isolated from Chinese mutant Musa acuminata Colla acuminata and double balbisiana (MA), Musa double acuminata cv. Pisang Mas (MAM), Musa acuminata cv. Pisang Awak (MAA), and Musa Basjoo Siebold (MBS), and Musa double acuminata and balbisiana-Prata (MAP) were investigated. Results exhibited that all starches exhibited high content of amylose (34.04–42.59%). According to the particle size, they were divided into medium (MA, MAM) (14.54–17.71 μm) and large (MAA, MBS, MAP) (23.01–23.82 μm) group. The medium group with A-type crystallization showed higher peak viscosity (PV), final viscosity, gel fracturability and gel hardness. For large group with B-type crystallization, the compact particle morphology, higher degree of crystallinity, short range order, gelatinization enthalpy, pasting temperature, lower porosity, water absorption capacity (WAC) and oil absorption capacity were found. In addition, the medium group with higher PV and gel hardness could be used as food thickening or gelling agents. The large group with higher Rc, short-range order, lower porosity and WAC could be potential to become raw material for resistant starch. All results showed the amylose content, had significant effect on the microstructure and physicochemical properties of starch samples. Outcomes in this investigation might provide a basis of theoretical application for industrial food production
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