排序方式: 共有8条查询结果,搜索用时 15 毫秒
1
1.
Binary Decision Diagrams (BDDs) are the state-of-the-art data structure for representation and manipulation of Boolean functions. In general, exact BDD minimization is NP-complete. For BDD-based technology, a small improvement in the number of nodes often simplifies the follow-up problem tremendously. This paper proposes an elitism-based evolutionary algorithm (EBEA) for BDD minimization. It can efficiently find the optimal orderings of variables for all LGSynth91 benchmark circuits with a known minimum size. Moreover, we develop a distributed model of EBEA, DEBEA, which obtains the best-ever variable orders for almost all benchmarks in the LGSynth91. Experimental results show that DEBEA is able to achieve super-linear performance compared to EBEA for some hard benchmarks. 相似文献
2.
In order to prepare fluorescent material for UV-LED used as illumination light source, two series of Eu2+ doped (1 mol%) alkaline earth aluminate phosphors CaxSr1−xAl2O4 and BaxSr1−xAl2O4 were prepared. The crystal structure, relative quantum efficiency(Qr), peak wavelength(λp), color tuning and chromaticity were investigated by XRD patterns and photoluminescence (PL) on samples prepared by solid solution system (s series) and powder mixing system (m series) respectively. For the s series, the synthesized CaxSr1−xAl2O4:Eu2+ powders show that the structure transforms from monoclinic to hexagonal at x?0.5, and λp increases from 442.3 to 529.7 nm with decreasing x. For the BaxSr1−xAl2O4:Eu2+ system, the structure transforms from monoclinic to hexagonal at x?0.3, and λp decreases from 520.5 to 502.2 nm continuously from x=0 to 1. The shift in λp could be explained by the crystal field effect, which is affected by different coulomb attractive forces due to the various fraction of alkaline earth cation in the host lattice. Different phosphor properties prepared by either solid solution or powder mixing methods were characterized by chromaticity measurements for both reflective and transmissive modes. 相似文献
3.
水下超声速气体射流气液两相复杂流动研究 总被引:2,自引:0,他引:2
本文实验研究了水下超声速气体射流气液两相复杂流动。利用高速摄影仪和电子相机分别实时记录了过膨胀超声速工况水下气体射流的喷射状态和整体形貌,显示了不同工况水下高速气体垂直射流的演化过程和动态不稳定性形貌。研究结果表明:在射流的初始段存在与射流内部复杂波系相关的激波反馈特性,激波反馈特性发生之前存在能量积聚的高频低幅的胀鼓过程,二者均随机发生;在射流的主体段,在气水掺混和卷吸大规模能量交换作用下,射流呈现随机的偏摆效应,并且偏摆受环境流场影响明显。 相似文献
4.
Ling-Wei Hsin Li-Te Chang Chien-Wei Chen Chia-Huei Hsu Hung-Wei Chen 《Tetrahedron》2005,61(2):513-520
A stereoselective synthesis of the ACNO partial structures of morphine has been developed. Palladium-catalyzed cyclization of carbamate 2 provided the tetracyclic (ACNO) 3-ethoxycarbonyl-9-methoxy-2,3,5,6,7,7a-hexahydro-1H-benzofuro[3,2-e]isoquinoline (14); while treatment of 5-(2-bromo-6-methoxyphenoxy)-2-methyl-1,2,3,4,5,6,7,8-octahydroisoquinoline (8) under the same reaction condition gave 8a-(2-hydroxy-3-methoxyphenyl)-1,2,3,4,6,7,8,8a-octahydroisoquinoline (11) via an unusual Claisen rearrangement. 9-Methoxy-3-methyl-2,3,5,6,7,7a-hexahydro-1H-benzofuro[3,2-e]isoquinoline (7) was successfully transformed to trans-octahydroisoquinoline 3 and cis-octahydroisoquinoline 4 via catalytical hydrogenation over PtO2 and chemical reduction with acidic NaBH4, respectively. 相似文献
5.
Shan-Tai Chen Shun-Shii Lin Li-Te Huang Sheng-Hsuan Hsu 《European Journal of Operational Research》2007
This paper presents novel algorithms for strategy optimization for deductive games. First, a k-way-branching (KWB) algorithm, taking advantage of a clustering technique, can obtain approximate results effectively. Second, a computer-aided verification algorithm, called the Pigeonhole-principle-based backtracking (PPBB) algorithm, is developed to discover the lower bound of the number of guesses required for the games. These algorithms have been successfully applied to deductive games, Mastermind and “Bulls and Cows.” Experimental results show that KWB outperforms previously published approximate strategies. Furthermore, by applying the algorithms, we derive the theorem: 7 guesses are necessary and sufficient for the “Bulls and Cows” in the worst case. These results suggest strategies for other search problems. 相似文献
6.
BAM (BaMgAl10O17:Eu2+) is a well-known phosphor used as the blue component of commercial fluorescent lamps. To improve the luminescence efficiency and chromatic properties of phosphors is a significant issue for applications in white LEDs; therefore, processing is one of the important topics to investigate. In this study, BAM (Ba0.98Eu0.02)MgAl10O17 phosphors were prepared by triethylamine (TEA) coprecipitation and solid-state reaction methods. Effects of synthesis temperature, annealing conditions in reductive atmosphere and AlF3 flux fraction on the crystal characteristics and luminescent properties of BAM phosphors were also discussed. The results showed that phosphors synthesized by TEA coprecipitation method had stronger effects on the above-mentioned properties. 相似文献
7.
Oscillation flow induced by underwater supersonic gas jets 总被引:1,自引:0,他引:1
Hong-Hui Shi Qiang Guo Chao Wang Ruo-Ling Dong Li-Te Zhang Hui-Xia Jia Xiao-Gang Wang Bo-Yi Wang 《Shock Waves》2010,20(4):347-352
This paper describes an experimental study on the oscillation flow characteristics of submerged supersonic gas jets issued
from Laval nozzles. The flow pattern during the jet development and the jet expansion feedback phenomenon are studied using
a high-speed camera and a pressure measurement system. The experimental results indicate that along the downstream distance,
the jet has three flow regimes: (1) momentum jet; (2) buoyant jet; (3) plume. In the region near the nozzle exit a so-called
bulge phenomenon is found. Bulging of the jet occurs many times before the more violent jet expansion feedback occurs. During
the feedback process, the jet diameter can become several times that of the original one depending on the jet Mach number.
The frequencies of the jet bulging and the jet expansion feedback are measured. 相似文献
8.
1