An Analysis of the Inertia Weight Parameter for Binary Particle Swarm Optimization

In particle swarm optimization (PSO), the inertia weight is an important parameter for controlling its search capability. There have been intensive studies of the inertia weight in continuous optimization, but little attention has been paid to the binary case. This paper comprehensively investigates the effect of the inertia weight on the performance of binary PSO (BPSO), from both theoretical and empirical perspectives. A mathematical model is proposed to analyze the behavior of BPSO, based on which several lemmas and theorems on the effect of the inertia weight are derived. Our research findings suggest that in the binary case, a smaller inertia weight enhances the exploration capability while a larger inertia weight encourages exploitation. Consequently, this paper proposes a new adaptive inertia weight scheme for BPSO. This scheme allows the search process to start first with exploration and gradually move toward exploitation by linearly increasing the inertia weight. The experimental results on 0/1 knapsack problems show that the BPSO with the new increasing inertia weight scheme performs significantly better than that with the conventional decreasing and constant inertia weight schemes. This paper verifies the efficacy of increasing inertia weight in BPSO. © 2016 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 component of this work in other works

3D-bar growth representations of all the defective mutants with C₁₂–C₂₄<i>n-</i>alkanes.

<p>Values on the horizontal axis profile the genotype of the mutants with single or multiple deletions of alkane hydroxylases; The Y-axis specifies the tested <i>n-</i>alkanes, coloring from black to dark blue black. The Z-axis of bar altitudes represents the OD₆₀₀ for the viability of each mutant. Sharp contrasts were symbolized using arrows when both <i>alkB1</i> and <i>alkB2</i> were knocked out, and cultivated in C₁₆ and C₁₈ alkane media, respectively.</p

Quantitative estimation of the SJTD-1-mediated degradation of <i>n</i>-hexadecane.

<p>The strain was cultured in BSM supplemented with 250 mg/L (▪), 500 mg/L (•), 1,000 mg/L (▴), and 2,000 mg/L (▾) of <i>n</i>-hexadecane at 30°C for seven days; Δ indicated as the <i>n</i>-alkane residues of the abiotic controls. Standard errors were calculated from three independent determinations.</p

Photoresponse of Donor/Acceptor Blends in Organic Transistors: A Tool for Understanding Field-Assisted Charge Separation in Small Molecule Bulk Heterojunction Solar Cells

Photoresponse and ambipolar charge transport in organic bulk heterojunctions (BHJ) is investigated using field-effect transistors (FET) based on two donors, poly­(3-hexylthiophene) (P3HT) and 3,6-bis­(5-(benzofuran-2-yl)­thiophen-2-yl)-2,5-bis­(2-ethylhexyl)­pyrrolo­[3,4-c]­pyrrole-1,4-dione (DPP­(TBFu)₂) blends with [6,6]-phenyl-C70-butyric acid methyl ester (PC₇₀BM) acceptor. Upon 100 mW/cm² AM 1.5 G illumination, P3HT:PC₇₀BM shows an equivalent hole and electron current together with a largely enhanced photoresponse in the FET. The DPP­(TBFu)₂:PC₇₀BM blends display an electron-dominating transport along with showing a relatively poor photoresponse in FETs upon irradiation. By comparing the two systems, it suggests that DPP­(TBFu)₂:PC₇₀BM possesses a less-efficient charge separation assisted by electric fields after exciton dissociation. The FET results correlate well to the solar cell device performance and provide further understanding and optimizing of solution-processed DPP small molecule solar cells

Characterization of the Medium- and Long-Chain <i>n</i>-Alkanes Degrading <i>Pseudomonas aeruginosa</i> Strain SJTD-1 and Its Alkane Hydroxylase Genes

<div><p>A gram-negative aliphatic hydrocarbon-degrading bacterium SJTD-1 isolated from oil-contaminated soil was identified as <i>Pseudomonas aeruginosa</i> by comparative analyses of the 16S rRNA sequence, phenotype, and physiological features. SJTD-1 could efficiently mineralize medium- and long-chain <i>n-</i>alkanes (C₁₂-C₃₀) as its sole carbon source within seven days, showing the most optimal growth on <i>n</i>-hexadecane, followed by <i>n</i>-octadecane, and <i>n</i>-eicosane. In 36 h, 500 mg/L of tetradecane, hexadecane, and octadecane were transformed completely; and 2 g/L <i>n</i>-hexadecane was degraded to undetectable levels within 72 h. Two putative alkane-degrading genes (gene 3623 and gene 4712) were characterized and our results indicated that their gene products were rate-limiting enzymes involved in the synergetic catabolism of C₁₂–C₁₆ alkanes. On the basis of bioinformatics and transcriptional analysis, two P450 monooxygenases, along with a putative AlmA-like oxygenase, were examined. Genetically defective mutants lacking the characteristic alkane hydroxylase failed to degrade <i>n</i>-octadecane, thereby suggesting a different catalytic mechanism for the microbial transformation of alkanes with chain lengths over C₁₈.</p></div

Comparison of alkane degradation by different strains.

<p>*with 0.005% yeast extract in the medium.</p><p>Comparison of alkane degradation by different strains.</p

Transcriptional levels of five putative AHs genes in wild type SJTD-1 and in three knockouts.

<p>Relative expression levels were determined with real-time RT-PCR. <i>16S rRNA</i> gene was used as the reference gene. The expression levels of genes in strain SJTD-1 (A), strain Mut<i>_alkB1</i> (B), strain Mut<i>_alkB2</i> (C), and strain Mut<i>_alkB1&2</i> (D) were shown. All strains were grown in different <i>n-</i>alkanes (C₁₂ to C₂₄ alkanes as the sole carbon source), and cells grown with sodium acetate were used as controls. Standard errors were calculated from three independent determinations.</p

Sequence alignment of alkane hydroxylases AlkB1 and AlkB2 from several strains and genetic distribution of five putative alkane hydroxylases in <i>P. aeruginosa</i> SJTD-1.

<p>Strains list: SJTD-1, <i>P. aeruginosa</i> SJTD-1; PAO1, <i>P. aeruginosa</i> PAO1; DQ8: <i>P. aeruginosa</i> DQ8; GPo1, <i>P. putida</i> Gpo1; P1, <i>P. putida</i> P1; CHAO: <i>P. fluorescens</i> CHAO; SK2, <i>Alcanivorax borkumensis</i> SK2; M-1, <i>Acinetobacter sp.</i> M-1; Q15, <i>Rohodococcus erythropolis</i> Q15; H37Rv, <i>Mycobacterium tuberculosis</i> H37Rv; DQ12-45-1b, <i>Dietzia sp.</i> DQ12-45-1b; E1, <i>Dietzia sp.</i> E1. (A) The conserved amino acid residues in all the sequences are indicated with a blue background, and the dark degree is in direct proportion to the degree of conservation. The three conserved histidine boxes (Hist-1, Hist-2, and Hist-3), and one HYG motif are underlined. The conserved amino acid associated with each position is shown below the alignment (created by Clustal Origin). (B) Phylogenetic relationship based on the complete amino acid sequences of AlkB1 and AlkB2 from <i>P. aeruginosa</i> SJTD-1 and other published AlkB amino acid sequences. The phylogenetic tree was determined using the Kimura two-parameter distance model, and bootstrap analysis was performed with 1,000 repetitions using MEGA 5.0. (C) Schematic profile of the genomic organization of AHs homologues in <i>P. aeruginosa</i> SJTD-1. <i>alkB1</i> and <i>alkB2</i>, alkane-1 monooxygenases (lawngreen and grey, separately); <i>P450-1</i> and <i>P450-2</i>, cytochrome P450s (red and blue, respectively); <i>almA</i>, AlmA-like monooxygenase (green); <i>tlpS</i>, methyl-accepting chemotaxis protein.</p

Growth curves of <i>P. aeruginosa</i> SJTD-1 in <i>n-</i>alkanes.

<p>Strain SJTD-1 was cultured in BSM supplemented with different concentrations (▪ 100 mg/L, • 250 mg/L, ▴ 500 mg/L, ▾ 1,000 mg/L, and ♦ 2,000 mg/L) of <i>n-</i>alkanes: <i>n</i>-decane (A), <i>n</i>-dodecane (B), <i>n</i>-tetradecane (C), <i>n</i>-hexadecane (D), <i>n</i>-octadecane (E), <i>n</i>-eicosane (F), <i>n</i>-docosane (G), and <i>n</i>-tetracosane (H) for seven days at 30°C. The data are expressed as mean values and the standard deviations are shown.</p

Mesoporous Hollow Nested Nanospheres of Ni, Cu, Co-Based Mixed Sulfides for Electrocatalytic Oxygen Reduction and Evolution

Nanostructured thiospinel-based transition metal sulfides with high-density active sites hold great application potentials as non-noble electrocatalysts. In this paper, high-performance bifunctional oxygen electrocatalysts of well-designed Ni, Cu, Co-based mixed sulfides, which combine two highly active thiospinels of NiCu2S4 and CuCo2S4, have been prepared successfully through solvothermal reaction, calcination, and the following sulfurization. The products of Ni, Cu, Co-based mixed sulfides present unique hollow structures with mesopores, in which several nanoparticles-assembled hollow nanospheres of 30–50 nm in thickness are nested one by one, forming multishell morphologies. Benefiting from the synergistic effect from combined NiCu2S4 and CuCo2S4 and the well-designed hollow structures with large electroactive surfaces/interfaces and efficient mass transportation, the obtained Ni, Cu, Co-based mixed sulfides exhibit remarkable electrocatalytic activities and excellent long-term durability toward not only oxygen reduction reaction (ORR) but also oxygen evolution reaction (OER). Regarding the overall oxygen-based electrocatalytic performance, the mixed sulfides present an extremely low potential difference (0.73 V) between the ORR and OER in KOH electrolyte, delivering significant superiority to their oxide counterparts and the commercial catalyst of Pt/C, as well as most of the oxygen bicatalysts reported recently. Therefore, the obtained Ni, Cu, Co-based mixed sulfides hold great promise as low-cost bifunctional catalysts with high efficiency for oxygen-based advanced energy storage systems