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Abstract: The waste collection vehicle routing problems with time windows and intermediate facilities (WCVRPTW-IF) is actually belong to a well-known generalization of VRP, the Multi-Depot Vehicle Routing Problem with Inter-Depot Routes (MDVRPI), which is a combinatorial optimization problem and holds a central place in reverse logistics management. In order to improve the route compactness, which is very important in practical application, we presents a clustering-based multiple ant colony system approach called CMACS algorithm to solve CVRPTW-IF. Our CMACS possesses a new strategy to construct solutions, called clustering-based strategy, and mutation operation. Tests are conducted on two standard instances. The results show that CMACS algorithm exhibits a robust behavior and the clustering-based strategy is effective. [Copyright &y& Elsevier]

Abstract: Using the centro-symmetry property of uniform linear array (ULA), we propose an algorithm that combines the weighted minimization with the unitary transformation to improve the performance of DOA estimation. Exploiting the result of the unitary transformation, more credible weights can be obtained and the jointly sparse constraint can be further enhanced. Moreover, the unitary transformation incorporates the forward–backward spatial smoothing, which improves the performance of the weighted minimization for correlated sources. Simulations demonstrate that the proposed method can achieve better performance in terms of resolution and estimation accuracy. [Copyright &y& Elsevier]

Landfill leachate is a highly contaminated and complex organic wastewater. It can be categorized into young (YL) and mature leachate (ML) based on the landfill age, with significant differences in the composition of organic matter, resulting from the significant differences in humification degree. To compare the organic composition of YL and ML, ESI FT-ICR MS was applied to systematically investigate their molecular composition, chemical properties, and structural characteristics. The molecular weight of YL organics was lower than that of ML organics. In addition, O/C and H/C distributions of YL and ML organics were significantly different. YL mainly consisted of CHO compounds and aliphatic compounds. ML mainly consisted of CHON compounds and high oxygen highly unsaturated and phenolic compounds. The unsaturation degree of YL organics was expressed by carbon double bond equivalents ((DBE-C)/C = −0.0336) and was not significantly different from that of ML (−0.0241), but nominal oxidation state of carbon (NOSC = −0.8010) and aromaticity (AI mod = 0.1254) of YL were significantly lower than of ML (NOSC = −0.0692; AI mod = 0.2464). In addition, YL and ML organics were rich in functional groups, but the YL organics contained more straight-chain structures. The ML organics contained fewer straight-chain structures, a larger number of benzene-ring structures, and more oxygen-containing functional groups. The more complex structural properties of ML organics may be the result of the transformation of YL organics after a long series of reactions, including electrocyclization, decarboxylation, and hydrogen abstraction reactions, which eventually increased the humification degree of leachate organic matter. [Display omitted] • Molecular composition of young and mature leachates is compared by FT-ICR MS. • Young and mature leachates have significant difference in NOSC and AI mod. • DOMs in mature leachate have more complex structure properties. • The DOM transformation from young to mature leachate is proposed. [ABSTRACT FROM AUTHOR]

Dynamic responses of high temperature superconducting bulk to inhomogeneous magnetic field distribution of permanent magnet guideway, as well as enlarged amplitude of magnetic field obtained by partially covering the permanent magnet guideway (PMG) with iron sheets in different thickness, are investigated. Experiments show that the instantaneous levitation force increases with the increase of the variation rate of magnetic field ( dB / dt ). Meanwhile, inhomogeneous magnetic field from PMG causes the decay of levitation force. The decay of levitation force almost increases linearly with the increase of alternating magnetic field amplitude. It should be very important for the application of high-speed maglev system. [ABSTRACT FROM AUTHOR]