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81.
We consider a project scheduling problem where a number of tasks need to be scheduled. The tasks share resources, satisfy precedences, and all tasks must be completed by a common deadline. Each task is associated with a cash flow (positive or negative value) from which a “net present value” is computed dependent upon its completion time. The objective is to maximize the cumulative net present value of all tasks. We investigate (1) Lagrangian relaxation methods based on list scheduling, (2) ant colony optimization and hybrids of (1) and (2) on benchmark datasets consisting of up to 120 tasks. Considering lower bounds, i.e., maximizing the net present value, the individual methods prove to be effective but are outperformed by the hybrid method. This difference is accentuated when the integrality gaps are large. 相似文献
82.
83.
The impact ionizing electroluminescence model of a unipolar double barrier structure has been developed. The electron density in the quantum well and the hole density generated in the collector region are based on electron current. The electroluminescence results from direct radiative recombination between the electrons and holes in the quantum well. The results show that a light on-off ratio of the electroluminescence can be obtained. 相似文献
84.
Wataru Ando Toshiya Furuhata Yukio Hanyu Toshikazu Takata 《Tetrahedron letters》1984,25(36):4011-4014
A variety of sulfur-containing five- and six-membered cyclic compounds was obtained by the acid-catalyzed and thermal reactions of an allene episulfide with various electrophiles. 相似文献
85.
K. Kakimoto M. Igarashi S. Hanyu Y. Sutoh T. Takemoto T. Hayashida Y. Hanada N. Nakamura R. Kikutake H. Kutami Y. Iijima T. Saitoh 《Physica C: Superconductivity and its Applications》2011,471(21-22):929-931
We have developed long RE1Ba2Cu3O7?X (RE123) coated conductors with large current capacity by the ion beam assisted deposition (IBAD) and the pulsed laser deposition using hot wall heating (HW-PLD) technique. As a result, we could fabricate an 8 m-long Gd1Ba2Cu3O7?X (Gd123) coated wire with the minimum and maximum critical current (Ic) of 951 A/cm-w and 1003 A/cm-w at 77 K, 0 T, respectively, measured in 0.7 m-long sections by the standard 4-probe technique. Furthermore, we succeeded in preparation of over 600 m-long Gd123 coated wire with the uniform Ic distribution over 600 A/cm-w. It had average, maximum and minimum Ic of 665, 698, 609 A/cm-w, respectively. The n-values of the sample showed the maximum Ic and minimum Ic were 40 and 36, respectively. As a result, we set the new world record of Ic × L value as 374535 A m (= 609 A × 615 m). The in-field performance of this long wire was quite high as well; the minimum Ic exceeded 50 A/cm-w at 77 K, 3 T. 相似文献
86.
针对一种用于快前沿直线脉冲变压器驱动源的多间隙气体开关,设计了针式和孔式两种预电离触发结构,获得了两种预电离结构下开关的自击穿特性和触发特性。实验结果表明:增加预电离针后,开关静态特性没有明显变化,开关自击穿电压平均值变化幅度小于3%;开关触发特性明显改善,开关工作电压150 kV、触发电压60 kV时,触发抖动减小约20%,触发阈值降低5~10 kV。对于针式预电离结构,实验研究了不同触发电压、工作气压、电离间隙距离时紫外光强度的变化规律,结果表明在电离间隙距离1.5~3.0 mm时,开关触发抖动小于2.0 ns,预电离效果明显。 相似文献
87.
In order to quantitatively study the jasmonate biosynthetic pathway, we chemically synthesized a pair of isotope mass probes and established a labeling protocol. The pair of mass probes used in our work were ω-bromoacetonylpyridinium bromide (BPB) and d(5)-ω-bromoacetonylpyridinium bromide (d(5)-BPB), which contain carboxylic acid reactive groups, isotopically labeled groups and permanent positive charges. High performance liquid chromatography (HPLC) and electrospray ionization quadrupole-time of flight mass spectrometry (ESI-QTOF-MS) were used for the detection of labeled standard mixtures and plant samples. In comparison to negative mode electrospray ionization detection of unlabeled analytes, the ESI signal of reverse charge labeled compounds was shown to improve by 20- to 80-fold. Accurate relative quantification was achieved as no isotopic effects of the different isotope labeled phytohormones during RP/SCX mixed-mode liquid chromatographic separation were observed. A data analysis method was established for analyzing metabolic pathways using our labeling strategy. We then applied our method and examined the jasmonate biosynthetic pathway of rice under salt stress and the premature senescence mutant. Here we found that under salt stress conditions, rice showed up-regulation in (13S)-hydroperoxyoctadecatrienoic acid (HOPT), cis-(+)-12-oxophytodienoic acid (OPDA), 3-oxo-2-(2'-pentenyl)-cyclopentane-1-octanoic acid (OPC-8) and jasmonoyl-valine (JA-Val) levels, while α-linolenic acid (LA) and jasmonic acid (JA) showed down-regulation, and three components (HPOT, OPC-8 and JA-Val) were accumulated. The premature senescence mutant showed up-regulation in all major components of the jasmonate biosynthetic pathway with the exception of LA, and an accumulation of HPOT, OPC-6 and JA-Val. This study demonstrates that our chemical stable isotope labeling strategy can be used as a powerful tool for metabolic pathway analysis of phytohormones in plants. 相似文献
88.
Novel magnetic chromium and sulfur co-doped TiO2 photocatalysts (M-Cr/S/TiO2) have been prepared by a sol?Cgel process, using magnetic hollow fly ash microspheres as support material. The crystal phase of M-Cr/S/TiO2 was characterized by X-ray diffraction, UV?Cvisible absorption spectroscopy, and transmission electron microscopy. The photocatalytic activity of the photocatalysts was examined by photodegradation of methyl orange in aqueous solution under visible light irradiation. The results showed that chromium and sulfur co-doped catalysts (Cr/S/TiO2) containing 0.60?% (atomic ratio) chromium and 1.2?% (atomic ratio) sulfur calcined at 450?°C for 2?h had high catalytic efficiency under visible irradiation. It is worth mentioning that the floating M-Cr/S/TiO2 catalyst had greater photocatalytic activity than Cr/S/TiO2 powder. Therefore, M-Cr/S/TiO2 is a promising, high-performing, visible-light-driven photocatalyst. 相似文献
89.
Based on fractional isospectral problems and general bilinear forms, the generalized fractional trace identity is presented. Then, a new explicit Lie algebra is introduced for which the new fractional integrable couplings of a fractional soliton hierarchy are derived from a fractional zero-curvature equation. Finally, we obtain the fractional Hamiltonian structures of the fractional integrable couplings of the soliton hierarchy. 相似文献
90.
Chongguang Cao Hanyu Zhang Yanling Ge 《Journal of Applied Mathematics and Computing》2014,46(1-2):169-179
Suppose ? is a right Ore domain with unity 1. In this paper, we investigate the existence of the group inverse of some anti-triangular block matrices over ? and obtain the sufficient and necessary conditions for such existence. Further, the representations of the group inverse for the following two classes are given. (i) , where CA=C; (ii) , where B ? exists and BA=BAB ? B. The results extend the earlier works of Liu et al. (in Appl. Math. Comput. 218:8978–8986, 2012) and Zhao et al. (in E. J. Linear Algebra 21:63–75, 2010). Some results in special cases are also generalized to any ring. 相似文献