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给定图$G$,对图$G$的每条边确定一个方向,称为$G$的定向图$G^\sigma$, $G$称为$G^\sigma$的基础图. $G^\sigma$的斜邻接矩阵$S(G^\sigma)$是反对称矩阵,其特征值是0或纯虚数. $S(G^\sigma)$所有特征值的$k$次幂之和称为$G^\sigma$的$k$阶斜谱矩,其中$k$是非负整数.斜谱矩序列可用于对图进行排序.本文主要研究定向树和定向单圈图的斜谱矩,并对这两类图的斜谱矩序列依照字典序进行排序.首先确定了直径为$d$的树作为基础图的所有定向树中,斜谱矩序最大的$2\lfloor\frac{d}{4}\rfloor$个图; 然后确定以围长为$g$的单圈图作为基础图的所有定向单圈图中, 斜谱矩序最大的$2\lfloor\frac{g}{4}\rfloor+1$个图. 相似文献
84.
《Proceedings of the Combustion Institute》2023,39(4):4457-4466
Hydrogen cyanide (HCN) is well-accepted as a main nitrogen-containing precursor from fuel nitrogen to nitrogen oxides. When using coal as fuel with a CuO-based oxygen carrier in chemical looping combustion (CLC), complex heterogeneous reactions exist among the system of HCN, O2, NO, H2O, and CuO particles. This work performs density functional theory (DFT) calculations to systematically probe the microscopic HCN heterogeneous reactions over the CuO particle surface. The results indicate that HCN is chemisorbed on the CuO surface, and the third dissociation step within the consecutive three-step HCN dissociations (HCN*→CN*→NCO*→N*) is the rate-determining step. Namely, the CN*/NCO* radicals can be deemed as an indicator of the performance of HCN removal due to their quite higher dissociation energies. With the existence of O2, H2O, and NO, the reaction mechanism of HCN conversion becomes extremely complex. Both DFT calculations and kinetic analyses determine that O2, NO, and H2O all significantly accelerate the consumption of CN*/NCO* radicals to produce various N-containing species (NOx or NH3) to different extents. Finally, a skeletal reaction network in a system of O2/NO/H2O/HCN is concluded, which clearly elucidates that CuO exhibits excellent catalytic activity toward HCN removal. 相似文献
85.
Wei Xu Ping Liu Chunhui Guo Chao Dong Xiuhua Zhang Shengfu Wang 《Mikrochimica acta》2013,180(11-12):1005-1011
We describe a molecularly imprinted electrochemical sensor for selective and sensitive determination of β2-agonists. It is making use of a combination of single-wall carbon nanotubes (SWNTs) with a molecularly imprinted sol–gel. The SWNTs were introduced in order to enhance electron transport and sensitivity. The imprinted sol–gel film with its specific binding sites acts as a selective recognition element and as a preconcentrator for β2-agonists. The morphology of the imprinted film was characterized by scanning electron microscopy. The optimized sensor displays high sensitivity and excellent selectivity for the β2-agonists as shown for their determination in human serum samples. Figure
A molecularly imprinted electrochemical sensor was constructed for selective and sensitive determination of β2-agonists. The optimized sensor displays high sensitivity and excellent selectivity for the β2-agonists as shown for their determination in human serum samples. 相似文献
86.
In this paper, we propose and experimentally demonstrate a novel optical packet switching scheme with one core router and two edge routers, in which an orthogonal frequency division multiplexing (OFDM) signal is generated as a label. In this experiment there are two transmission spans, each span consists of 50-km SMF-28 and an erbium-doped optical fiber amplifier (EDFA) without dispersion management. A 10 Gb/s on-off keying (OOK) optical payload and a 2.5 Gb/s OFDM optical label are generated, encapsulated, and transmitted in the first span. And then old label is replaced by new label, the generated new optical packet after transmission over the second span is detached and detected. The transmission performance of the optical label and payload is experimentally investigated at the ingress router, core router and egress router. 相似文献
87.
In order to research the transport characteristic of photoelectrons in different-structure transmission-mode GaAs photocathodes, the energy and emergence angle spreads of photoelectrons reaching the band-bending region are calculated and the photoemission properties are analyzed. Based on the established atomic configuration models and ionized impurity scattering formulas of the uniform-doping and exponential-doping photocathodes, the trajectories of photoelectrons in different GaAs photocathodes have been calculated. The results show that, the emergence angle spread of the exponential-doping photocathode is more centralized than that of the uniform-doping one. The influence of the built-in electric field on the photoemission is obvious in the short-wave region. The built-in electric field not only increases the quantum efficient, but also improves the resolution of photocathode. This research can be propitious to investigate the photoemission mechanism, and to analyze the effect of the excited photoelectrons on the image intensifier performance. 相似文献
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Wan Qiang Cao 《Physica A》2012,391(4):1105-1110
The shoving model and the Vogel-Fulcher relation are employed to derive correlation of the fragility with the mechanical moduli for glass-forming simple liquids. The result shows that a liquid with smaller fragility will have larger ratio of K∞/G∞ in dilute liquid system. Based on radial distribution function with the Lennard-Jones potential modified by the Gaussian potential with a second minimum, fragility of the supercooled simple liquid is derived from the correlation between viscosity and shear modulus via configurational entropy. The results demonstrate that the fragility is determined by two parts: thermodynamic components and mechanical moduli. For a weak Gaussian potential liquid, the fragility is proportional to the Tg, while for a strong one, the fragility is inversely proportional to the Tg, and the Gaussian potential will increase fragility. 相似文献