444 research outputs found

    Optimal analog wavelet bases construction using hybrid optimization algorithm

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    An approach for the construction of optimal analog wavelet bases is presented. First, the definition of an analog wavelet is given. Based on the definition and the least-squares error criterion, a general framework for designing optimal analog wavelet bases is established, which is one of difficult nonlinear constrained optimization problems. Then, to solve this problem, a hybrid algorithm by combining chaotic map particle swarm optimization (CPSO) with local sequential quadratic programming (SQP) is proposed. CPSO is an improved PSO in which the saw tooth chaotic map is used to raise its global search ability. CPSO is a global optimizer to search the estimates of the global solution, while the SQP is employed for the local search and refining the estimates. Benefiting from good global search ability of CPSO and powerful local search ability of SQP, a high-precision global optimum in this problem can be gained. Finally, a series of optimal analog wavelet bases are constructed using the hybrid algorithm. The proposed method is tested for various wavelet bases and the improved performance is compared with previous works.Peer reviewedFinal Published versio

    Generalized Completed Local Binary Patterns for Time-Efficient Steel Surface Defect Classification

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    © 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted ncomponent of this work in other works.Efficient defect classification is one of the most important preconditions to achieve online quality inspection for hot-rolled strip steels. It is extremely challenging owing to various defect appearances, large intraclass variation, ambiguous interclass distance, and unstable gray values. In this paper, a generalized completed local binary patterns (GCLBP) framework is proposed. Two variants of improved completed local binary patterns (ICLBP) and improved completed noise-invariant local-structure patterns (ICNLP) under the GCLBP framework are developed for steel surface defect classification. Different from conventional local binary patterns variants, descriptive information hidden in nonuniform patterns is innovatively excavated for the better defect representation. This paper focuses on the following aspects. First, a lightweight searching algorithm is established for exploiting the dominant nonuniform patterns (DNUPs). Second, a hybrid pattern code mapping mechanism is proposed to encode all the uniform patterns and DNUPs. Third, feature extraction is carried out under the GCLBP framework. Finally, histogram matching is efficiently accomplished by simple nearest-neighbor classifier. The classification accuracy and time efficiency are verified on a widely recognized texture database (Outex) and a real-world steel surface defect database [Northeastern University (NEU)]. The experimental results promise that the proposed method can be widely applied in online automatic optical inspection instruments for hot-rolled strip steel.Peer reviewe

    Bubbles or cycles? Housing price dynamics in China’s major cities

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    Based on the monthly data of 35 cities during the period 2006−2017, this study adopts a recursive forward looking method to detect the presence of housing bubbles and investigate their potential cyclical patterns in China’s large and medium sized cities. Empirical results show that the number of cities reporting housing bubbles has been increasing since 2013, before it declined in 2017. Regarding regional disparities of housing bubbles, 1st-tier and 1.5-tier cities have higher probability than 2nd-tier cities for housing bubbles. In general, eastern region cities have more housing bubbles than central and western region cities, which may indicate the problem of shrinking cities China is facing nowadays. Bubble signals for market correction in major cities and municipalities seemed alarming in particular for the period 2013−2016, however it is difficult to conclude if the market adjustment in 2017 indicates a cyclical pattern. First published online 19 December 201

    Lactobacillus pentosus expressing porcine lactoferrin elevates antibacterial activity and improves the efficacy of vaccination against Aujeszky’s disease

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    In this study, Lactobacillus pentosus expressing porcine lactoferrin (pLF) was tested for in vitro antibacterial activity and for its ability to enhance immunity induced by an orally administered Aujeszky’s disease virus (ADV) vaccine. The cDNA encoding N-terminus of pLF was cloned into a Lactobacillus-specific plasmid to produce L. pentosus pLF expressing transformants (pPG612.1-pLFN/ L. pentosus). The antimicrobial activity of the recombinant pLF protein inhibited bacterial growth in vitro. The supernatant of pPG612.1-pLF-N/L. pentosus had an inhibitory effect on Staphylococcus aureus strain CVCC26003, Bacillus subtilis strain CVCC63501, Escherichia coli strain CVCC10141 and Salmonella enterica ssp. enterica Choleraesuis strain CVCC79102, while it did not inhibit the growth of Lactobacillus casei strain ATCC393. A mouse model was established to test the effectiveness of the orally administered probiotic L. pentosus recombinant strain in the gastrointestinal tract. Mice were immunised with an attenuated porcine Aujeszky’s disease virus (ADV) vaccine. Serum antibody levels determined using a mouse Aujeszky’s disease IgG ELISA showed that IgG levels were significantly higher in the pPG612.1-pLFN/L. pentosus group than in the PBS and Lactobacillus pentosus groups at days 7 and 21 (P < 0.01) and at day 14 (P < 0.05), indicating that this oral recombinant strain can improve the effectiveness of the vaccine and play a role in immune enhancement through humoral immunity. These results suggest that the recombinant Lactobacillus pentosus not only has the beneficial characteristics of lactic acid bacteria but also produces biologically functional lactoferrin

    Thermal Properties of Liquid Iron at Conditions of Planetary Cores

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    Thermal properties of iron at high pressures (P) and temperatures (T) are essential for determining the internal structure and evolution of planetary cores. Compared to its solid counterpart, the liquid phase of iron is less studied and existing results exhibit large discrepancies, hindering a proper understanding of planetary cores. Here we use the formally exact urn:x-wiley:21699097:media:jgre21861:jgre21861-math-0019 thermodynamic integration approach to calculate thermal properties of liquid iron up to 3.0 TPa and 25000 K. Uncertainties associated with theory are compensated by introducing a T-independent pressure shift based on experimental data. The resulting thermal equation of state agrees well with the diamond anvil cell (DAC) data in the P-T range of measurements. At higher P-T it matches the reduced shock wave data yet deviates considerably from the extrapolations of DAC measurements, indicating the latter may require further examinations. Moreover, the calculated heat capacity and thermal expansivity are substantially lower than some recent reports, which have important ramifications for understanding thermal evolutions of planetary cores. Using Kepler-36b as a prototype, we examine how a completely molten core may affect the P-T profiles of massive exoplanets. By comparing the melting slope and the adiabatic slope along the iron melting line, we propose that crystallization of the cores of massive planets proceeds from the bottom-up rather than the top-down

    Sustainable Management of Spent Hydroprocessing Catalyst

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    Increasing demand for high-quality transportation fuels and stringent environmental standards have resulted in the significantly increased quantity of spent hydroprocessing catalysts, which require the sustainable management. To minimize the generation of hazardous wastes, the spent hydroprocessing catalysts can be regenerated via oxidative regeneration or reactivated via the rejuvenation process. If the catalytic activity cannot be restored, it can be utilized as a source of other useful materials, and/or metals in the spent catalyst are recovered. Finally, the stabilized residues shall be disposed by using an environmentally sound method. Citation: Yang, C., Wu, J., Wang, W., Li, B., Zhang, B., and Ding, Y. (2018). Sustainable Management of Spent Hydroprocessing Catalyst. Trends in Renewable Energy, 4(1), 90-95. DOI:10.17737/tre.2018.4.1.006
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